APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

30 Nov 1998

Volume 73, Issue 22, pp. 3181-3305

Page 1 of 2 Pages Next Page | Jump to Page
back to top
RSS Feeds

Excitation energy-dependent optical characteristics of InGaN/GaN multiple quantum wells

Yong-Hoon Cho, J. J. Song, S. Keller, U. K. Mishra, and S. P. DenBaars

Appl. Phys. Lett. 73, 3181 (1998); http://dx.doi.org/10.1063/1.122711 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have systematically studied the optical properties of InGaN/GaN multiple quantum wells (MQWs) at 10 K under different excitation conditions using photoluminescence (PL), PL excitation, and time-resolved PL spectroscopy. We found that the PL emission consists of a strong main peak at 2.80 eV and a much weaker and broader secondary peak at ∼ 2.25 eV. We observed that the peak position blueshifts and the spectral width narrows for the main peak when the excitation energies are varied from 3.81 eV (above the band gap of the AlGaN capping layer) to 2.99 eV (below the band gap of the GaN barrier layers). The intensity ratio of the main peak to the secondary peak also varied with excitation energy. The two observed emission peaks originate from different layers of the MQWs. Time-integrated and time-resolved PL revealed that the InGaN-related spontaneous emission processes are strongly affected by inhomogeneity and carrier localization in the MQWs. From these studies under varying excitation energies, we conclude that interface-related defects and roughness may play an important role in the InGaN-related emission mechanism during the carrier transfer between different layers of the MQWs. © 1998 American Institute of Physics.
Show PACS
78.66.Fd III-V semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ey III-V semiconductors
78.55.Cr III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Comparison of terahertz waveforms measured by electro-optic and photoconductive sampling

Sang-Gyu Park, M. R. Melloch, and A. M. Weiner

Appl. Phys. Lett. 73, 3184 (1998); http://dx.doi.org/10.1063/1.122712 (3 pages) | Cited 18 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Terahertz waveforms measured by free-space electro-optic sampling and a photoconductive dipole antenna were carefully compared. We show that the difference between the waveforms could be explained quantitatively in terms of carrier lifetime and frequency dependent response of the photoconductive receiver antenna. © 1998 American Institute of Physics.
Show PACS
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
84.40.Ba Antennas: theory, components and accessories
85.60.Gz Photodetectors (including infrared and CCD detectors)
42.79.Pw Imaging detectors and sensors

Fast, low insertion-loss optical switch using lithographically defined electromagnetic microactuators and polymeric passive alignment structures

R. A. Norwood, J. Holman, L. W. Shacklette, S. Emo, N. Tabatabaie, and H. Guckel

Appl. Phys. Lett. 73, 3187 (1998); http://dx.doi.org/10.1063/1.122713 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A micro-optoelectromechanical switch that combines microactuator technology developed via the Lithographie Galvanformung Abformung process with lithographically defined polymeric alignment elements is described. The multimode optical switch achieves submillisecond switching times, low insertion loss (<1 dB), low cross talk (<70 dB), low voltage (3 V), and wavelength independence. © 1998 American Institute of Physics.
Show PACS
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks
42.79.Sz Optical communication systems, multiplexers, and demultiplexers
42.82.Cr Fabrication techniques; lithography, pattern transfer
07.10.Cm Micromechanical devices and systems
42.81.Dp Propagation, scattering, and losses; solitons
42.70.Jk Polymers and organics

High-Q whispering gallery modes from a composite system of GaAs quantum well and fused silica microsphere

Xudong Fan, Andrew Doran, and Hailin Wang

Appl. Phys. Lett. 73, 3190 (1998); http://dx.doi.org/10.1063/1.122714 (3 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate a composite system consisting of a GaAs quantum well structure placed in the evanescent field of a fused silica microsphere and show evanescent coupling between excitons in the quantum well and high-Q whispering gallery modes of the composite system. The composite system allows separate engineering of photonic and electronic confinement and can take advantage of high-Q factor and small mode volume of fused silica microspheres. © 1998 American Institute of Physics.
Show PACS
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.66.Fd III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
71.35.-y Excitons and related phenomena
78.55.Cr III-V semiconductors

Nonlinear absorption of Cr4+:YAG studied with lasers of different pulsewidths

Sang-Hoon Yim, Dong-Ryeol Lee, Bum Ku Rhee, and Doseok Kim

Appl. Phys. Lett. 73, 3193 (1998); http://dx.doi.org/10.1063/1.122715 (3 pages) | Cited 12 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A saturable absorber Cr4+:YAG, used for a passive Q switching of Nd:YAG laser was studied in order to understand the physical mechanism of nonlinear absorption (photobleaching). An optical bleaching experiment was carried out using the two pulsed lasers with duration of pico- and nanoseconds at 1.064 μm wavelength. Experimental results were compared with numerical analysis of theoretical rate equations with all relevant energy levels. The inclusion of intersystem crossing between singlet- and triplet-excited states with reasonable rate of transition kisc was necessary to explain the difference in the saturation behaviors for nanosecond and picosecond laser pulses. © 1998 American Institute of Physics.
Show PACS
42.50.Md Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation, and self-induced transparency
42.55.Px Semiconductor lasers; laser diodes
42.55.Rz Doped-insulator lasers and other solid state lasers
42.70.Hj Laser materials
42.60.Fc Modulation, tuning, and mode locking

Excitation of Er3+ emission by host glass absorption in sputtered films of Er-doped Ge10As40Se25S25 glass

S. Ramachandran and S. G. Bishop

Appl. Phys. Lett. 73, 3196 (1998); http://dx.doi.org/10.1063/1.122716 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Photoluminescence and photoluminescence excitation (PLE) spectroscopy have been carried out on the ∼1550 nm 4I13/2→4I15/2 Er3+ emission from thin films of Er-doped As40Ge10Se25S25 glass deposited on silicon substrates by radio frequency sputtering. The PLE spectroscopy shows that the Er3+ emission is excited in the 1-μm-thick film by the Urbach absorption edge of the host glass rather than direct absorption by the Er3+ intra-4f shell transitions. This enables the use of a broad range of pump wavelengths and novel pumping geometries. Comparison of the PLE spectra of the Er emission obtained before and after a rapid thermal anneal (RTA) clearly manifests a blue shift in the band gap induced by the RTA process. These results reveal that the broad band Er PLE mechanism discovered recently in Er-doped bulk chalcogenide glasses and attributed to host glass Urbach edge optical absorption and energy transfer mediated by native defects also occurs in sputtered films of Er-doped chalcogenide glass. © 1998 American Institute of Physics.
Show PACS
78.66.Jg Amorphous semiconductors; glasses
78.55.Hx Other solid inorganic materials
71.55.Jv Disordered structures; amorphous and glassy solids
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
back to top
RSS Feeds

Interaction of vacuum-arc-generated macroparticles with a liquid surface

André Anders

Appl. Phys. Lett. 73, 3199 (1998); http://dx.doi.org/10.1063/1.122717 (3 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The concept of trapping vacuum-arc-generated macroparticles by a liquid is introduced. Experiments have been performed using a pulsed vacuum arc plasma source operating with a carbon cathode. Vacuum pump oil was used as the trapping liquid in vacuum. It was experimentally shown that trapping did not work as anticipated: a substantial number of particles experienced elastic reflection from the liquid surface. With simplified energy and momentum balances it is shown that the liquid behaves increasingly like a solid when the approaching particle is fast. A significant portion of its kinetic energy is transformed into deformation energy which can reappear as kinetic energy of the reflected particle. Particle reflection is likely to be additionally supported by a Leidenfrost-type effect: a thin oil vapor layer of relatively high pressure can be formed between the liquid surface and the macroparticle caused by the macroparticle’s high temperature. © 1998 American Institute of Physics.
Show PACS
68.03.Fg Evaporation and condensation of liquids
61.46.-w Structure of nanoscale materials
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
52.50.Dg Plasma sources
52.25.Vy Impurities in plasmas
back to top
RSS Feeds

Controlled doping of phthalocyanine layers by cosublimation with acceptor molecules: A systematic Seebeck and conductivity study

M. Pfeiffer, A. Beyer, T. Fritz, and K. Leo

Appl. Phys. Lett. 73, 3202 (1998); http://dx.doi.org/10.1063/1.122718 (3 pages) | Cited 17 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigate the doping of vanadyl–phthalocyanine by a fluorinated form of tetracyano-quinodimethane as an example of controlled doping of thin organic dye films by cosublimation of matrix and dopant. The electrical parameters of the films derived from conductivity and Seebeck measurements show that the results largely follow standard models used to describe the doping of crystalline semiconductors; e.g., a smooth shift of the Fermi level towards the valence states with increasing doping is observed. Other effects, like the superlinear increase of conductivity with the molar doping ratio, need the inclusion of additional effects like percolation. © 1998 American Institute of Physics.
Show PACS
73.61.Ph Polymers; organic compounds
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.50.Lw Thermoelectric effects
61.72.up Other materials

Termination, surface structure and morphology of the molecular beam epitaxially grown HgTe(001) surface

S. Oehling, M. Ehinger, T. Gerhard, C. R. Becker, G. Landwehr, M. Schneider, D. Eich, H. Neureiter, R. Fink, M. Sokolowski, and E. Umbach

Appl. Phys. Lett. 73, 3205 (1998); http://dx.doi.org/10.1063/1.122719 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The surface structure of molecular beam epitaxially grown HgTe(001) has been studied under in situ ultrahigh vacuum conditions. The as-grown samples were investigated by means of x-ray photoelectron spectroscopy (XPS), spot profile analysis of low-energy electron diffraction, reflection of high-energy electron diffraction and scanning tunneling microscopy (STM). They exhibited a c(2×2) surface reconstruction with an additional weak (2×1) component in both diffraction experiments. The surface was shown by XPS to be terminated with Hg atoms. In addition, by means of STM experiments, we have been able to resolve the atomic structure of the reconstructed surface and to detect domain boundaries along the [1math0] direction whose local symmetry is twofold and, therefore, the probable cause of the weak (2×1) reconstruction. © 1998 American Institute of Physics.
Show PACS
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology
79.60.Bm Clean metal, semiconductor, and insulator surfaces

“Contact epitaxy” observed in supported nanoparticles

M. Yeadon, M. Ghaly, J. C. Yang, R. S. Averback, and J. M. Gibson

Appl. Phys. Lett. 73, 3208 (1998); http://dx.doi.org/10.1063/1.122720 (3 pages) | Cited 38 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have observed the formation of heteroepitaxial interfacial layers between silver nanoparticles and a single crystal copper surface by a phenomenon we term “contact epitaxy.” Upon depositing Ag nanoparticles (5–20 nm diameter) onto clean (001) Cu in an ultrahigh vacuum in situ transmission electron microscope, a thin (111)-oriented layer of Ag was detected at the interface between the substrate and particles. Molecular dynamics simulations reveal that the epitaxial layers form within picoseconds of impact, with rapid alignment arising from mechanical relaxation of the highly stressed interface formed upon initial contact. The simulations also show that multiple grains form in the nanoparticle as a consequence of this relaxation process. The unique structure of the nanoparticles, induced by contact epitaxy, is expected to significantly influence physical properties such as interfacial bonding, diffusion, chemical activity, and electrical transport, as well as forming a nucleus for grain growth and epitaxy which we also observe. Due to its simple origin, the phenomenon should also apply to materials systems beyond the field of nanoparticles with implications for cluster deposition, adhesion, rheology, and catalysis. © 1998 American Institute of Physics.
Show PACS
68.35.Ct Interface structure and roughness
61.46.-w Structure of nanoscale materials
68.55.-a Thin film structure and morphology
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.15.Cd Deposition by sputtering
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Multistable antiferroelectric liquid-crystal optical modulator

Valery Vorflusev and Satyendra Kumar

Appl. Phys. Lett. 73, 3211 (1998); http://dx.doi.org/10.1063/1.122721 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An electro-optical element based on antiferroelectric liquid crystal (AFLC) has been prepared by photopolymerization-induced anisotropic phase separation of a solution of an AFLC and a prepolymer. It consists of two adjacent layers, one comprised of the isotropic polymer and the other of the AFLC aligned by surface treatment of the adjacent substrate. The electro-optical properties show that these devices are either optically monostable or multistable (at zero field) with maximum memory angle of ∼15°. A qualitative model to describe the origin of memory in these AFLC/polymer composites is discussed. © 1998 American Institute of Physics.
Show PACS
42.79.Kr Display devices, liquid-crystal devices
42.79.Hp Optical processors, correlators, and modulators
42.70.Df Liquid crystals
42.70.Jk Polymers and organics
64.75.-g Phase equilibria
64.70.M- Transitions in liquid crystals
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

Aluminum-induced crystallization of amorphous silicon on glass substrates above and below the eutectic temperature

Oliver Nast, Tom Puzzer, Linda M. Koschier, Alistair B. Sproul, and Stuart R. Wenham

Appl. Phys. Lett. 73, 3214 (1998); http://dx.doi.org/10.1063/1.122722 (3 pages) | Cited 84 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The achievement of high-quality continuous polycrystalline silicon (poly-Si) layers onto glass substrates by using aluminum-induced crystallization is reported. The crystallization behavior of dc sputtered amorphous silicon on glass induced by an Al interface layer has been investigated above and below the eutectic temperature of 577 °C. Secondary electron micrographs in combination with energy-dispersive x-ray microanalysis show that annealing below this temperature leads to the juxtaposed Al and Si layers exchanging places. The newly formed poly-Si layer is fully crystallized and of good crystalline quality, according to Raman spectroscopy and transmission electron microscopy investigations. At 500 °C, the time needed to crystallize a 500-nm-thick Si layer is as short as 30 min. By annealing above the eutectic temperatures, layer exchange is not as pronounced and the newly formed Al layer is found to contain a network of crystallized Si. © 1998 American Institute of Physics.
Show PACS
68.55.-a Thin film structure and morphology
61.43.Dq Amorphous semiconductors, metals, and alloys
61.72.Cc Kinetics of defect formation and annealing
81.05.Cy Elemental semiconductors
81.05.Gc Amorphous semiconductors
78.66.Db Elemental semiconductors and insulators
78.30.Am Elemental semiconductors and insulators

Diagnostics of “colossal” magnetoresistance manganite films by Raman spectroscopy

V. B. Podobedov, D. B. Romero, A. Weber, J. P. Rice, R. Schreekala, M. Rajeswari, R. Ramesh, T. Venkatesan, and H. D. Drew

Appl. Phys. Lett. 73, 3217 (1998); http://dx.doi.org/10.1063/1.122723 (3 pages) | Cited 24 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Polarized Raman scattering by phonons is used to characterize thin films prepared by laser ablation of La1−xCaxMnO3 targets. It was found that, in the temperature range from 6 to 300 K, phonon spectra of La0.7Ca0.3MnO3 films exhibit observable differences from those in bulk materials (microcrystalline ceramics and single crystals). A significant difference was found in the spectra of “as-grown” films compared to those annealed in oxygen at 800 °C. The observed Raman peaks and their linewidths exhibit an irregular temperature dependence near Tc. A correlation of Raman data with magnetization of the sample was also found. © 1998 American Institute of Physics.
Show PACS
75.47.De Giant magnetoresistance
78.30.Hv Other nonmetallic inorganics
78.66.Nk Insulators
75.50.Dd Nonmetallic ferromagnetic materials
75.70.Ak Magnetic properties of monolayers and thin films
72.20.My Galvanomagnetic and other magnetotransport effects
63.20.D- Phonon states and bands, normal modes, and phonon dispersion
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Diffusion coefficient of Al in metastable, amorphous Al–Pt phase

Z. Radi, J. L. Lábár, and P. B. Barna

Appl. Phys. Lett. 73, 3220 (1998); http://dx.doi.org/10.1063/1.122724 (3 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Diffusion data for amorphous binary alloys are scarce in the literature. There are no data available for the diffusion of Al in Al–Pt amorphous phase known to the authors. High-temperature successive deposition of components was used in the present experiments to reveal the elementary processes of reactive diffusion forming the metastable amorphous phase and to determine the diffusion coefficient of Al in this phase: D(α) = (1.2±0.4)×10−10×exp[−(6.9±0.1)×104J mol−1/RT]m2 s−1. This value, taken from thin film experiments, can be considered as a good approximation to the bulk diffusion coefficient. © 1998 American Institute of Physics.
Show PACS
66.30.Ny Chemical interdiffusion; diffusion barriers
68.55.Nq Composition and phase identification
68.35.Fx Diffusion; interface formation

Sub-5 nm gold dot formation using retarding-field single ion deposition

M. Hori, R. G. Woodham, and H. Ahmed

Appl. Phys. Lett. 73, 3223 (1998); http://dx.doi.org/10.1063/1.122725 (3 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Gold dots of 2.5 nm mean diameter and 0.8 nm standard deviation have been fabricated successfully on chromium oxide (CrOx) thin films. The CrOx thin films were deposited on Si substrates by sputtering and gold dots were subsequently deposited by a retarding-field single ion deposition (RSID) technique. The formation of gold dots has been investigated systematically with landing energies from 100 to 900 eV and doses from 10 to 40 C/m2. The dot diameter and density could be controlled by varying the landing energy and dose of gold ions arriving on the surface. The formation of single electron devices, quantum dots, nanopillars, and other nanoscale device structures is proposed using the RSID technique. © 1998 American Institute of Physics.
Show PACS
81.15.Jj Ion and electron beam-assisted deposition; ion plating
68.55.-a Thin film structure and morphology
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Effect of the hydrogen on the intrinsic stress in hydrogenated amorphous carbon films deposited from an electron cyclotron resonance plasma

B. Racine, M. Benlahsen, K. Zellama, P. Goudeau, M. Zarrabian, and G. Turban

Appl. Phys. Lett. 73, 3226 (1998); http://dx.doi.org/10.1063/1.122726 (3 pages) | Cited 13 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The intrinsic stresses have been investigated in detail in particular diamondlike carbon films prepared by chemical vapor deposition assisted by electron cyclotron resonance plasma, as a function of the substrate bias and sample thickness in relation with the H content and bonding. Combined infrared absorption, elastic recoil detection analysis, and residual stress measurements are used to fully characterize the films in their as deposited state. The results indicate clearly that both the low and high biased samples exhibit compressive stresses. The stresses are found to be higher in the high biased films and are affected not only by the [H]/[C] ratio but also by the C–H and C–C volumetric distortions. © 1998 American Institute of Physics.
Show PACS
68.60.Bs Mechanical and acoustical properties
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.66.-w Optical properties of specific thin films

Nanometer-scale imaging of domains in ferroelectric thin films using apertureless near-field scanning optical microscopy

Charles Hubert and Jeremy Levy

Appl. Phys. Lett. 73, 3229 (1998); http://dx.doi.org/10.1063/1.122727 (3 pages) | Cited 26 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Images of nanometer-scale ferroelectric domains in BaxSr1−xTiO3 thin films are obtained with 30 Å spatial resolution using apertureless near-field scanning optical microscopy (ANSOM). The images exhibit inhomogeneities in the ferroelectric polarization over the smallest scales that can be observed, and are largely uncorrelated with topographic features. The application of an in-plane static electric field causes domain reorientation and domain-wall motion over distances as small as 40 Å. These results demonstrate the promise of ANSOM for imaging near-atomic-scale polarization fluctuations in ferroelectric materials. © 1998 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
77.80.Dj Domain structure; hysteresis
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ej Polarization and depolarization
back to top
RSS Feeds

Incorporation of indium during molecular beam epitaxy of InGaN

T. Böttcher, S. Einfeldt, V. Kirchner, S. Figge, H. Heinke, D. Hommel, H. Selke, and P. L. Ryder

Appl. Phys. Lett. 73, 3232 (1998); http://dx.doi.org/10.1063/1.122728 (3 pages) | Cited 36 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the incorporation of In during growth of InxGa1−xN by molecular beam epitaxy under varying In/Ga flux ratios and with different film thicknesses. The incorporation efficiency studied by energy dispersive x-ray microanalysis, high-resolution x-ray diffraction and photoluminescence spectroscopy is strongly affected by the chosen fluxes of Ga and N and is limited by the excess of nitrogen compared to gallium. Furthermore, thick films exhibit a decrease of the In content in growth direction. The behavior can be explained by considering the different stabilities of the two binary compounds InN and GaN. © 1998 American Institute of Physics.  
Show PACS
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Nq Composition and phase identification
61.66.Bi Elemental solids
61.66.Dk Alloys
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors

Persistent photoconductivity in Si delta-doped GaAs at low doping concentration

C. Y. Chen, Tineke Thio, K. L. Wang, K. W. Alt, and P. C. Sharma

Appl. Phys. Lett. 73, 3235 (1998); http://dx.doi.org/10.1063/1.122729 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In addition to the persistent photoconductivity (PPC) attributed to DX centers in GaAs delta-doped with Si, a weak PPC (WPPC) with a PPC carrier density independent of Si-doping concentration has been generally reported at ambient atmosphere, but the nature of the deep states responsible has not been elucidated. Here, we present the results of a detailed study of the WPPC in δ-GaAs:Si at low-doping densities, NSi ≈ 1–3×1012 cm−2, and ambient pressure. It is concluded that the WPPC does not arise from DX centers but from another deep defect, which is DX-like in the sense that it can be metastably excited. The presence of two distinct DX-like states is apparent from two separate annealing temperatures of the PPC, Ta ≈ 50 K and Tb ≈ 230 K; to the best of our knowledge, the latter is the highest annealing temperature observed in the AlGaAs:Si system. © 1998 American Institute of Physics.
Show PACS
72.40.+w Photoconduction and photovoltaic effects
72.80.Ey III-V and II-VI semiconductors
71.55.Eq III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments

Depth-resolved cathodoluminescence study of ZnxCd1−xSe epilayer grown on (001) InP by metal organic chemical vapor phase deposition

X. B. Zhang, H. K. Won, and S. K. Hark

Appl. Phys. Lett. 73, 3238 (1998); http://dx.doi.org/10.1063/1.122730 (3 pages) | Cited 5 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Optical properties of zincblende structured ZnxCd1−xSe epilayer grown on InP by metal organic chemical vapor phase deposition at temperatures of 360, 400, and 440 °C are investigated with low temperature cathodoluminescence spectroscopy (CL). Both near band gap and deep level emissions are found for the samples grown at 400 °C and above, but deep level emissions are absent for the sample grown at 360 °C. We conclude that the growth temperature should be kept below the temperature at which InP begins to decompose and diffusion of III–V constituents into the epilayer occurs. Evidence of this diffusion comes from an analysis of depth resolved CL studies, which shows that the deep level emissions occur mainly at the epilayer/substrate interface. By monitoring the ratio of the intensity of the deep level emissions to that of the near band emissions, we find that this ratio is larger for samples grown at high temperatures than those at low temperatures. Indium diffusion from the substrate into the epilayer is most likely the source of these deep levels. © 1998 American Institute of Physics.
Show PACS
78.66.Hf II-VI semiconductors
81.05.Dz II-VI semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
81.15.Kk Vapor phase epitaxy; growth from vapor phase
66.30.Ny Chemical interdiffusion; diffusion barriers
71.55.Gs II-VI semiconductors

Electrochemical fabrication of n-Si/Au Schottky junctions

G. Oskam, D. van Heerden, and P. C. Searson

Appl. Phys. Lett. 73, 3241 (1998); http://dx.doi.org/10.1063/1.122731 (3 pages) | Cited 23 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the electrochemical deposition of gold films onto n-type silicon. Gold deposition occurs through progressive nucleation and diffusion limited growth. A high density of gold nuclei was obtained by using a short potential pulse to −1.6 V(Ag/AgCl), and subsequent growth was performed at about −1.1 V(Ag/AgCl) where the growth rate is kinetically limited. Transmission electron microscopy showed that high quality, continuous gold films were formed with an average grain size on the order of 50–70 nm. The electrical properties of the electrochemically deposited Si/Au Schottky junctions are comparable to junctions prepared by evaporation or sputtering techniques. © 1998 American Institute of Physics.
Show PACS
73.40.Ns Metal-nonmetal contacts
73.30.+y Surface double layers, Schottky barriers, and work functions
81.15.Pq Electrodeposition, electroplating
81.05.Bx Metals, semimetals, and alloys
68.55.-a Thin film structure and morphology

Structure and hydrogen content of stable hot-wire-deposited amorphous silicon

A. M. Brockhoff, E. H. C. Ullersma, H. Meiling, F. H. P. M. Habraken, and W. F. van der Weg

Appl. Phys. Lett. 73, 3244 (1998); http://dx.doi.org/10.1063/1.122732 (3 pages) | Cited 9 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thin-film transistors incorporating a hot-wire chemical-vapor-deposited silicon layer have been shown to exhibit superior electronic stability as compared to glow-discharge-deposited amorphous silicon devices. Hot-wire-deposited silicon films of various thicknesses (37–370 nm) on silicon dioxide were investigated. The films are structurally inhomogeneous. Raman measurements and transmission electron microscopy show that isolated cone-shaped crystals grow within a primarily amorphous layer. The amorphous interface region has a low hydrogen content of 2.0±0.2 at. %, while the films exhibit an enhanced hydrogen concentration in the surface region. The bond-angle distribution in the amorphous phase is comparable to that of device-quality glow-discharge-deposited amorphous silicon. © 1998 American Institute of Physics.
Show PACS
61.43.Dq Amorphous semiconductors, metals, and alloys
68.55.-a Thin film structure and morphology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.Gc Amorphous semiconductors
81.05.Cy Elemental semiconductors
85.30.Tv Field effect devices
78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.66.Jg Amorphous semiconductors; glasses

Evidence on the formation of a heavily Ge-doped layer in Pd/Ge-based ohmic contact to pseudomorphic high electron mobility transistor

Jong-Lam Lee and Yi-Tae Kim

Appl. Phys. Lett. 73, 3247 (1998); http://dx.doi.org/10.1063/1.122733 (3 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Microstructural evidence on the formation of a heavily Ge-doped layer below Pd/Ge-based ohmic contact to AlGaAs/InGaAs pseudomorphic high electron mobility transistor was obtained. The contact resistivity is decreased by two orders of magnitude as InGaAs channel is intermixed. This originates from the formation of Au2Al and Au7Ga2 compounds below the contacts during annealing, via production of group III vacancies. The vacancies play a role in producing free electrons by the incorporation of Ge atoms, resulting in intermixing of InGaAs as well as reduction of contact resistivity. © 1998 American Institute of Physics.
Show PACS
85.30.Tv Field effect devices
73.40.Ns Metal-nonmetal contacts
73.40.Cg Contact resistance, contact potential
61.72.J- Point defects and defect clusters
61.72.Cc Kinetics of defect formation and annealing

Electron paramagnetic resonance evidence for reversible transformation of thermal donor into shallow donor-type center in hydrogen-implanted silicon

B. Rakvin, B. Pivac, R. Tonini, F. Corni, and G. Ottaviani

Appl. Phys. Lett. 73, 3250 (1998); http://dx.doi.org/10.1063/1.122734 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron paramagnetic resonance spectrum of the proton-related thermal donor (TD) assigned as NL8 paramagnetic center has been detected at 110 K after heat treatment of the hydrogen-implanted Czochralski-Si at 773 K. The effect of temperature on reversible transformations of the anisotropic spectrum of NL8 center into the isotropic singlet line was studied in the temperature region from 110 to 240 K. The analysis of the singlet provides an evidence that this signal originates from the proton-related shallow donor type at g = 1.9987. The changes in the linewidth have been used to evaluate the parameters [1/τ = 0.66×1012 exp(−ΔE/kT);ΔE = 169 meV] for thermally activated electron emission to the conduction band from the second donor state of the NL8 center. These results represent direct experimental evidence of reversible transformation of the TD+ charged center into the shallow donor-type center. © 1998 American Institute of Physics.
Show PACS
76.30.Lh Other ions and impurities
71.55.Cn Elemental semiconductors
61.72.uf Ge and Si
61.72.Cc Kinetics of defect formation and annealing

Gallium vacancies and the growth stoichiometry of GaN studied by positron annihilation spectroscopy

K. Saarinen, P. Seppälä, J. Oila, P. Hautojärvi, C. Corbel, O. Briot, and R. L. Aulombard

Appl. Phys. Lett. 73, 3253 (1998); http://dx.doi.org/10.1063/1.122735 (3 pages) | Cited 40 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have applied positron spectroscopy to study the formation of vacancy defects in undoped n-type metal organic chemical vapor deposition grown GaN, where the stoichiometry was varied. Ga vacancies are found in all samples. Their concentration increases from 1016 to 1019 cm−3 when the V/III molar ratio increases from 1000 to 10 000. In nitrogen rich conditions Ga lattice sites are thus left empty and Ga vacancies are abundantly formed. The creation of Ga vacancies is accompanied by the decrease of free electron concentration from 1020 to 1016 cm−3, demonstrating their role as compensating centers. © 1998 American Institute of Physics.
Show PACS
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.J- Point defects and defect clusters
78.70.Bj Positron annihilation
61.66.Bi Elemental solids
61.66.Dk Alloys
71.55.Eq III-V semiconductors
81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
Page 1 of 2 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close