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14 Oct 1996

Volume 69, Issue 16, pp. 2309-2441

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GaAs‐based multiple quantum well tunneling injection lasers

X. Zhang, Y. Yuan, A. Gutierrez‐Aitken, and P. Bhattacharya

Appl. Phys. Lett. 69, 2309 (1996); http://dx.doi.org/10.1063/1.117507 (3 pages) | Cited 2 times

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We report the modulation characteristics of multiple quantum well tunneling injection lasers designed for 0.98 μm emission wavelength. Electrons are injected into the active region through a single barrier via tunneling. The active region has four quantum wells with different well widths. Improved high frequency performance, compared to similar separate confinement heterostructure lasers, has been demonstrated. The modulation response at 21 GHz is above 0 dB and the extrapolated −3 dB modulation bandwidth is ∼30 GHz under pulsed bias. © 1996 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
78.66.Fd III-V semiconductors
73.40.Gk Tunneling

Adjustable surface emission from AlGaAs/GaAs laser diodes based on first‐order‐grating coupled surface mode emission

A. Golshani, A. Köck, S. Freisleben, C. Gmachl, E. Gornik, and L. Korte

Appl. Phys. Lett. 69, 2312 (1996); http://dx.doi.org/10.1063/1.117508 (3 pages) | Cited 2 times

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Strongly improved surface emitting laser diodes based on surface mode emission are presented. A first‐order‐grating was utilized for the excitation of the surface modes. This results in an efficient quasi‐single‐beam surface emission with low divergence and a significant narrowing in the emission spectrum. A variation in the emission wavelength of up to 4 nm is achieved by adjusting the surface waveguide thickness, which demonstrates the wavelength selection mechanism of the SME technique. The decisive advantage of the SME laser diodes in comparison to DFB/DBR laser diodes is their high flexibility in fabrication, which makes them very suitable for wavelength division multiplexing applications. © 1996 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
85.60.Jb Light-emitting devices

Electroluminescence of epitaxial perylene films

Y. Toda and H. Yanagi

Appl. Phys. Lett. 69, 2315 (1996); http://dx.doi.org/10.1063/1.117509 (3 pages) | Cited 26 times

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A multilayered electroluminescent device was constructed with ordered perylene thin films as an emission layer. The epitaxial perylene film was prepared by vapor deposition onto the KCl (001) surface, then removed from the KCl substrate and sandwiched between the hole‐transport layer coated on an indium tin oxide electrode and Al top electrode. In this epitaxial layer, the perylene molecules oriented their molecular planes perpendicular to the electrode surfaces. This epitaxial device emitted an electroluminescence in the longer wavelengths of 560–580 nm due to the ordered dimeric structure. On the other hand, the device with polycrystalline perylene films exhibited an electroluminescence mainly below 500 nm. © 1996 American Institute of Physics.
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78.60.Fi Electroluminescence
78.66.Qn Polymers; organic compounds
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Raman polarization‐selective feedback schemes for all‐optical microwave frequency standards

Z. D. Liu, P. Juncar, D. Bloch, and M. Ducloy

Appl. Phys. Lett. 69, 2318 (1996); http://dx.doi.org/10.1063/1.117510 (3 pages) | Cited 4 times

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All‐optical locking of the frequency difference between two laser diodes onto a Raman transition is demonstrated. The properties of Raman‐type polarization spectroscopy are discussed and exemplified in the cases of the 3.036 GHz Raman resonance of the 85Rb D2 line. The generation of a polarization‐selective Raman resonant optical feedback ensures the Raman optical locking of the slave diode laser onto the master oscillator. © 1996 American Institute of Physics.
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42.55.Ye Raman lasers
42.55.Px Semiconductor lasers; laser diodes
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
06.30.Ft Time and frequency

A wideband coherent terahertz spectroscopy system using optical rectification and electro‐optic sampling

Ajay Nahata, Aniruddha S. Weling, and Tony F. Heinz

Appl. Phys. Lett. 69, 2321 (1996); http://dx.doi.org/10.1063/1.117511 (3 pages) | Cited 240 times

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We present a scheme for exploiting the nonresonant second‐order nonlinearities in electro‐optic media to extend the bandwidth of coherent spectroscopy in the far‐infrared using ultrafast laser pulses. Using optical rectification and electro‐optic sampling in 〈110〉 ZnTe for the generation and coherent detection of freely propagating THz radiation, respectively, we have demonstrated spectral sensitivity beyond 3 THz. This was accomplished by achieving phase matching for both optical rectification and electro‐optic sampling over a broad range of THz frequencies. © 1996 American Institute of Physics.
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
78.20.Jq Electro-optical effects

Carrier transport in asymmetrically confined 1.55 μm multiple quantum well laser structures

M. Zimmermann, S. Krämer, A. Hangleiter, F. Steinhagen, H. Hillmer, and H. Burkhard

Appl. Phys. Lett. 69, 2324 (1996); http://dx.doi.org/10.1063/1.117512 (3 pages) | Cited 2 times

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Asymmetrically confined multiple quantum well laser structures have recently been very successful in reaching high modulation bandwidths up to 26 GHz, reported in the InGaAs/InGaAlAs material system. We have measured the effective carrier transport time in structures of this kind by performing parasitic‐free optical modulation experiments. The result is one specific transport time for each confinement layer width. We show that down to layer widths of about 100 nm this effective time for both types of carriers is given by a pure diffusion process for InGaAs/InGaAlAs. Finally, a diffusion constant for the barrier/confinement carriers results in InGaAlAs material which is in very good agreement with reported mobilities. © 1996 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
42.60.Rn Relaxation oscillations and long pulse operation
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Absorption enhancement in silicon‐on‐insulator waveguides using metal island films

Howard R. Stuart and Dennis G. Hall

Appl. Phys. Lett. 69, 2327 (1996); http://dx.doi.org/10.1063/1.117513 (3 pages) | Cited 87 times

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We report the degree to which the resonances associated with metal island films can be used to enhance the sensitivity of very thin semiconductor photodetectors. The island films can couple incident light into the waveguide modes of the detector, resulting in increased absorption. To characterize the coupling, silver‐, gold‐, and copper‐island layers were formed on the surface of a thin‐film photodetector fabricated in the 0.16 μm thick silicon layer of a silicon‐on‐insulator (SOI) wafer. The copper islands gave the best result, producing more than an order of magnitude enhancement in the photocurrent for light of wavelength 800 nm. The enhancements appear to be due primarily to coupling between the metal island resonances and the waveguide modes supported by the SOI structure. © 1996 American Institute of Physics.
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85.60.Dw Photodiodes; phototransistors; photoresistors
42.82.Et Waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers

Normal‐incidence epitaxial SiGeC photodetector near 1.3 μm wavelength grown on Si substrate

F. Y. Huang and Kang L. Wang

Appl. Phys. Lett. 69, 2330 (1996); http://dx.doi.org/10.1063/1.117514 (3 pages) | Cited 17 times

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We report on the fabrication of photodetectors with a response near 1.3 μm wavelength using an epitaxial SiGeC alloy grown on a Si substrate. The active absorption layer of the SiGeC/Si pin photodiode consists of a strained SiGeC alloy with a Ge content of 60% and a thickness of 800 Å. The device exhibits a peak response at 0.85 μm with the response extending to 1.3 μm and a cutoff wavelength at around 1.55 μm. The photocurrent response of the device versus reverse bias voltage saturates at 0.5 V. The leakage current density at the saturation voltage is 70 pA/μm2. These results may shed some light on Si‐based SiGeC alloys for photodetector applications in the 1.3–1.55 μm wavelength range. © 1996 American Institute of Physics.
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42.79.Pw Imaging detectors and sensors
85.60.Gz Photodetectors (including infrared and CCD detectors)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Second‐order optical nonlinearities in dilute melt proton exchange waveguides in z‐cut LiNbO3

Torben Veng, Torben Skettrup, and Kjeld Pedersen

Appl. Phys. Lett. 69, 2333 (1996); http://dx.doi.org/10.1063/1.117515 (3 pages) | Cited 6 times

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Planar optical waveguides with different refractive indices are made in z‐cut LiNbO3 with a dilute proton exchange method using a system of glycerol containing KHSO4 and lithium benzoate. The optical second‐order susceptibilities of these waveguides are measured by detecting the 266 nm reflected second‐harmonic signal generated by a 532 nm beam directed onto the waveguide surface. It is found for this kind of waveguides that in the waveguide region all the second‐order susceptibilities take values of at least 90% of the original LiNbO3 values for refractive index changes less than ∼0.013 at the 632.8 nm wavelength, whereas the susceptibilities are strongly reduced for larger index changes. © 1996 American Institute of Physics.
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42.82.Et Waveguides, couplers, and arrays
42.65.An Optical susceptibility, hyperpolarizability
42.70.Mp Nonlinear optical crystals

Dispersive surface plasmon microscopy for the characterization of ultrathin organic films

Harald Knobloch, Günther von Szada‐Borryszkowski, Sabine Woigk, Andreas Helms, and Ludwig Brehmer

Appl. Phys. Lett. 69, 2336 (1996); http://dx.doi.org/10.1063/1.117516 (2 pages) | Cited 11 times

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We report on experiments, applying a novel microscopy method for ultrathin‐film characterization which uses the dispersion properties of plasmon surface polaritons (PSP) as a contrast giving mechanism. In contrast to prior methods, we apply white light instead of a laser for resonant PSP excitation. For a given incident angle and an area of given thickness, a narrow spectral band of the incident light is at resonance for PSP excitation. Therefore, we obtain images with areas of different thickness appearing in different color. As an example, we present microscopic images taken from a thin Cu–phthalocyanine film, evaporated onto solid support through a mask. In addition, we compare the obtained images to theoretical considerations on the contrast mechanism. © 1996 American Institute of Physics.
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68.35.B- Structure of clean surfaces (and surface reconstruction)
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
77.84.Jd Polymers; organic compounds

Resonance fluorescence of a single molecule under near field excitation

Railing Chang, Wunshain Fann, and S. H. Lin

Appl. Phys. Lett. 69, 2338 (1996); http://dx.doi.org/10.1063/1.117517 (3 pages) | Cited 4 times

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We report here theoretical investigations on the resonance fluorescence of a two‐level molecule, probed by the near field optical microscopy technique in illumination mode. The proposed model considers the influence of a coated tapered fiber probe on the radiative properties of the molecule. It is observed that both the radiative decay rate as well as the fluorescence power depend sensitively on the position and direction of the transition dipole of the molecule. © 1996 American Institute of Physics.
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33.50.Dq Fluorescence and phosphorescence spectra
07.79.Fc Near-field scanning optical microscopes

Fast modeling of the low‐pressure capacitively coupled radio‐frequency discharge based on the nonlocal approach

S. V. Berezhnoi, I. D. Kaganovich, L. D. Tsendin, and V. A. Schweigert

Appl. Phys. Lett. 69, 2341 (1996); http://dx.doi.org/10.1063/1.117518 (3 pages) | Cited 6 times

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The results of modeling a low‐pressure capacitively coupled radio‐frequency (rf) discharge based on the nonlocal approach are reported. The approximation employed enables fast modeling (FM) of the electron distribution function. The solution of the full problem, which consists of calculation of the electron distribution, rf, and stationary electric fields, and of the plasma density profile, for simple atomic gas takes ∼10 min on the IBM PC 486DX2/66. To check the validity of the FM the full scale Monte Carlo modeling was performed. The results of the fast and the full scale modeling are in agreement. © 1996 American Institute of Physics.
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52.25.Dg Plasma kinetic equations
52.65.Pp Monte Carlo methods
52.80.Pi High-frequency and RF discharges

Highly tetrahedral amorphous carbon films with low stress

M. Chhowalla, Y. Yin, G. A. J. Amaratunga, D. R. McKenzie, and Th. Frauenheim

Appl. Phys. Lett. 69, 2344 (1996); http://dx.doi.org/10.1063/1.117519 (3 pages) | Cited 67 times

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We have deposited boronated highly tetrahedral amorphous carbon (ta‐C:B) films with low stress using a filtered cathodic vacuum arc. The sp3 fraction, hardness, and resistivity were measured as a function of the ion energy and were found to reach a maximum above 50 eV for B concentrations of 2% and 4%. The most significant result we found was that highly tetrahedral a‐C:B film (sp3≊80%) with low stress (1–3 GPa) with B concentrations up to 4% could be obtained. The B in the films was found to be predominantly (≊75%) sp2 bonded. Additionally, the stress in the films did not vary with the ion energy or sp3 fraction unlike in regular ta‐C films. © 1996 American Institute of Physics.
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61.43.Dq Amorphous semiconductors, metals, and alloys
68.60.Bs Mechanical and acoustical properties
73.61.Jc Amorphous semiconductors; glasses
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Low‐temperature synthesis of Ge nanocrystals in zeolite Y

H. Miguez, V. Fornés, F. Meseguer, F. Marquez, and C. Lopez

Appl. Phys. Lett. 69, 2347 (1996); http://dx.doi.org/10.1063/1.117520 (3 pages) | Cited 11 times

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A method for obtaining Ge nanocrystals has been developed using the porous structure of zeolite Y as a matrix. Samples were obtained by reduction of GeO2 nanocrystals, previously grown in zeolite α cages, in H2 at 470 °C. This is apparently the lowest GeO2 reduction temperature reported and is probably due to the influence of the host. Ge crystallites so formed present an absorption edge at 2.2 eV, which is shifted ∼1.4 eV with respect to the bulk value. A softening and an asymmetric broadening of the Raman peak were also observed. We can estimate an average diameter of 3 nm for the Ge nanocrystals from both results. © 1996 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
61.46.-w Structure of nanoscale materials
78.30.Am Elemental semiconductors and insulators

The effect of current density and stripe length on resistance saturation during electromigration testing

R. G. Filippi, R. A. Wachnik, H. Aochi, J. R. Lloyd, and M. A. Korhonen

Appl. Phys. Lett. 69, 2350 (1996); http://dx.doi.org/10.1063/1.117521 (3 pages) | Cited 17 times

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Resistance saturation as a function of current density and stripe length has been investigated for a two‐level structure with Ti/TiN/AlCu/Ti/TiN stripes and interlevel W stud vias. A simple model relating the resistance change at saturation to the current density and stripe length is formulated for structures with short stripe lengths and blocking boundaries at both ends. Experimental results for stripe lengths of 25, 50, or 100 μm are in good agreement with the model predictions. © 1996 American Institute of Physics.
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66.30.Qa Electromigration
73.61.At Metal and metallic alloys
85.40.Ls Metallization, contacts, interconnects; device isolation

Dielectric response process in relaxor ferroelectrics

Hong Gui, Xiaowen Zhang, and Binglin Gu

Appl. Phys. Lett. 69, 2353 (1996); http://dx.doi.org/10.1063/1.117522 (3 pages) | Cited 9 times

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The dielectric constant ε∗(ω,T)=ε′(ω,T)+iε″(ω,T) of relaxor ferroelectrics is simulated by the Monte Carlo method. It is proved that the polar microregions switch among different polarization directions as a whole under the electrical field, giving rise to the high dielectric constant. The relaxor characteristics are caused by the randomly distributed interactions between the polar microregions. Factors which influence the dielectric response process are discussed. © 1996 American Institute of Physics.
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77.22.Ch Permittivity (dielectric function)
77.80.Fm Switching phenomena

Preferential precipitation sequence of metastable phase during crystallization of (Fe0.99Mo0.01)78Si9B13 metallic glass

Jian‐Min Li, Ming‐Xiu Quan, and Zhuang‐Qi Hu

Appl. Phys. Lett. 69, 2356 (1996); http://dx.doi.org/10.1063/1.117523 (2 pages) | Cited 7 times

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A preferential precipitation sequence of metastable phase formation during crystallization of an amorphous alloy (Fe0.99Mo0.01)78Si9B13 was revealed as following: α‐Fe(Si, Mo) (bcc) → (Fe,Mo)3B (BCT), (Fe,Mo)3.5B (BCT), and (Fe,Mo)23B6 (fcc) →Fe2B. An ordering process of atom cluster occurs prior to the crystallization. Above experimental sequence of crystallization of (Fe0.99Mo0.01)78Si9B13 metallic glass could be understood in terms of the Gaskell model. There is a high strain (0.33%) in the α‐Fe(Si, Mo) (bcc) grain with 37 nm, and the strain relaxation leads to the distortion in the lattice parameter of nanocrystallite. © 1996 American Institute of Physics.
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81.30.Mh Solid-phase precipitation
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
61.66.Dk Alloys
75.50.Bb Fe and its alloys

Critical thickness of GaN thin films on sapphire (0001)

Chinkyo Kim, I. K. Robinson, Jaemin Myoung, Kyuhwan Shim, Myung‐Cheol Yoo, and Kyekyoon Kim

Appl. Phys. Lett. 69, 2358 (1996); http://dx.doi.org/10.1063/1.117524 (3 pages) | Cited 50 times

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Synchrotron x‐ray diffraction was employed to measure the lattice constants a and c of GaN films grown with an AlN buffer layer on sapphire (0001) over a thickness range of 50 Å to 1 μm. We used multiple reflections and a least‐squares fit method for high reliability. As the thickness increased, the lattice constant a increased from 3.133 Å to 3.196 Å and c decreased from 5.226 Å to 5.183 Å. The expected trend was fitted to an equilibrium theory, allowing the critical thickness of GaN on AlN to be estimated at 29 Å ± 4 Å in good agreement with a theoretical prediction. © 1996 American Institute of Physics.
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61.05.cm X-ray reflectometry (surfaces, interfaces, films)
68.55.-a Thin film structure and morphology
07.85.Qe Synchrotron radiation instrumentation

Novel spectromicroscopy: Pt–GaP studies by spatially resolved internal photoemission with near‐field optics

J. Almeida, Tiziana dell’Orto, C. Coluzza, G. Margaritondo, O. Bergossi, M. Spajer, and D. Courjon

Appl. Phys. Lett. 69, 2361 (1996); http://dx.doi.org/10.1063/1.117525 (3 pages) | Cited 12 times

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The combination of internal photoemission and near‐field optics is proposed as a generally applicable approach to study the lateral variations of solid interface properties such as energy barriers and electron‐hole recombination rates. A successful test on Pt–GaP is described in which topographic and nontopographic phenomena are revealed, in particular recombination rate variations and small lateral changes of the Schottky barrier height. © 1996 American Institute of Physics.
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07.60.-j Optical instruments and equipment
07.79.Fc Near-field scanning optical microscopes
72.40.+w Photoconduction and photovoltaic effects
73.30.+y Surface double layers, Schottky barriers, and work functions

Damage to epitaxial GaN layers by silicon implantation

H. H. Tan, J. S. Williams, J. Zou, D. J. H. Cockayne, S. J. Pearton, and R. A. Stall

Appl. Phys. Lett. 69, 2364 (1996); http://dx.doi.org/10.1063/1.117526 (3 pages) | Cited 70 times

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Ion channeling and cross‐sectional transmission electron microscopy were used to study the extent and nature of Si ion implantation damage in epitaxial GaN layers at liquid nitrogen temperature. Results indicate that displacement damage produced by the implantation undergoes substantial dynamic annealing during implantation. As a result, at moderate implantation doses residual implantation damage consists of a dense network of secondary defects, such as clusters and loops, which are a consequence of incomplete annihilation of implantation‐produced defects. Amorphous layers can be produced, but the doses required are extremely high (≳1016 cm−2) and amorphization appears to ‘‘nucleate’’ at the surface. © 1996 American Institute of Physics.
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61.72.up Other materials
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Influence of microstructure on electromigration dynamics in submicron Al interconnects: Real‐time imaging

S. P. Riege, J. A. Prybyla, and A. W. Hunt

Appl. Phys. Lett. 69, 2367 (1996); http://dx.doi.org/10.1063/1.117527 (3 pages) | Cited 6 times

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Systematic studies of the influence of local microstructure on electromigration (EM) dynamics in submicron Al (0.5 wt % Cu) interconnects were performed using in situ transmission electron microscopy. This approach has allowed us to observe, in real time, voids forming, growing, migrating, pinning, failing a runner, and healing all with respect to the detailed local microstructure of the runners. In this letter, we report and describe how grain boundaries dramatically influence almost all aspects of EM‐induced void and failure dynamics in submicron runners. In addition, we report that EM voids nucleate at grain boundaries long before open‐circuit failures occur. These findings have important implications for electromigration modeling. © 1996 American Institute of Physics.
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85.40.Ls Metallization, contacts, interconnects; device isolation
66.30.Qa Electromigration
68.55.-a Thin film structure and morphology

Calculation of diamond chemical vapor deposition region in C–H–O phase diagram

E. G. Rakov

Appl. Phys. Lett. 69, 2370 (1996); http://dx.doi.org/10.1063/1.117640 (3 pages) | Cited 1 time

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Thermodynamic calculations of graphite yield at the interaction of gaseous components of the C–H–O system were performed. Their results proved to be in satisfactory agreement with experimental data published on the lower concentration boundary of the diamond deposition region. The calculations indicate an influence of the substrate temperature, total pressure, and concentrations of inert and active additives on this boundary’s location. These data confirm an inference that a diamond deposition mechanism might include spontaneous growth‐etch cycles due to fluctuations of the gas concentrations. © 1996 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.ub Fullerenes and related materials
82.60.-s Chemical thermodynamics

Microhardness study of amorphous hydrogenated boron carbide deposited on a cathode substrate by plasma deposition

Shu‐Han Lin, Bernard J. Feldman, and Dong Li

Appl. Phys. Lett. 69, 2373 (1996); http://dx.doi.org/10.1063/1.117641 (3 pages) | Cited 17 times

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We have grown amorphous hydrogenated boron carbide thin films on a cathode substrate by rf plasma decomposition of diborane and methane. The chemical composition, infrared absorption, optical absorption, microhardness, and adhesion of these thin films were measured. As a function of increasing diborane concentration in the feedstock, we observe increasing boron and decreasing hydrogen concentrations, increasing infrared absorption at 1300 cm−1 due to boron icosahedra, increasing optical band gaps, dramatically increased microhardness, and increased adhesion to the underlying substrates of these thin films. These results provide evidence that the presence of boron icosahedra increases microhardness, adhesion, and optical band gaps. © 1996 American Institute of Physics.
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62.20.Qp Friction, tribology, and hardness
68.60.Bs Mechanical and acoustical properties
78.66.Jg Amorphous semiconductors; glasses
61.43.Dq Amorphous semiconductors, metals, and alloys

Room‐temperature electroluminescence from Si/Ge/Si1−xGex quantum‐well diodes grown by molecular‐beam epitaxy

H. Presting, T. Zinke, A. Splett, H. Kibbel, and M. Jaros

Appl. Phys. Lett. 69, 2376 (1996); http://dx.doi.org/10.1063/1.117642 (3 pages) | Cited 16 times

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Tunable room‐temperature electroluminescence, photocurrent, and photoluminescence in the near infrared (λ∼1.3 μm) has been observed from Ge/Si/Ge/Si1−xGex quantum‐well (QW) diodes grown by molecular‐beam epitaxy. The QWs are grown on a p+‐doped 〈100〉‐Si substrate and consist of two thin Ge wells separated by a thicker Si middle layer, and the whole structure is embedded by two Si0.85Ge0.15 alloy layers. Our theoretical analysis of the data suggests that the strength of the spectra is linked to states localized at the interface. © 1996 American Institute of Physics.
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78.60.Fi Electroluminescence
78.66.Fd III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

A donorlike deep level defect in Al0.12Ga0.88N characterized by capacitance transient spectroscopies

W. Götz, N. M. Johnson, M. D. Bremser, and R. F. Davis

Appl. Phys. Lett. 69, 2379 (1996); http://dx.doi.org/10.1063/1.117643 (3 pages) | Cited 20 times

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Si‐doped, n‐type heteroepitaxial layers of Al0.12Ga0.88N grown by metalorganic chemical vapor deposition on SiC substrates were characterized by capacitance transient spectroscopies. Conventional deep level transient spectroscopy (DLTS) reveals the presence of a dominant deep level with an activation energy for electron emission to the conduction band of (0.61±0.02) eV. The activation energy of this deep level displays a pronounced field dependence as determined from double‐correlation DLTS (DDLTS), which is indicative of a deep donor level in n‐type semiconductors. A deep level is observed by optical‐DLTS (O‐DLTS) with a threshold energy for electron photoemission to the conduction band of 0.77 eV, which appears to be of identical origin as the dominant deep level detected by DLTS. Two additional deep levels are detected with O‐DLTS in the upper half of the band gap of our Al0.12Ga0.88N sample with threshold energies of 0.83 and 1.01 eV. © 1996 American Institute of Physics.
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71.55.Eq III-V semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
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