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29 Jan 1996

Volume 68, Issue 5, pp. 579-723

Page 2 of 2 Pages Previous Page | Jump to Page

Thermal stability of the silicon doping of GaAs grown on (111)A oriented substrates

L. Pavesi and M. Henini

Appl. Phys. Lett. 68, 652 (1996); http://dx.doi.org/10.1063/1.116498 (3 pages) | Cited 2 times

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The thermal stability of the silicon doping of (111)A GaAs, grown by molecular beam epitaxy under different As overpressures, is studied by electrical and photoluminescence measurements. Annealing treatments were performed at 1028 K for 8 hr in As‐poor conditions. It is found that the silicon doping of (111)A GaAs is unstable; annealing turns the doping from p type to n type in p‐type doped samples and increases the compensation in n‐type doped samples. The role of the point defects in the process is discussed. © 1996 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
71.55.Eq III-V semiconductors

Rapid thermal annealing of arsenic‐implanted Si0.6Ge0.4 alloys: Temperature effects

V. S. Tishkov, P. I. Gaiduk, S. Yu. Shiryaev, and A. Nylandsted Larsen

Appl. Phys. Lett. 68, 655 (1996); http://dx.doi.org/10.1063/1.116499 (3 pages) | Cited 8 times

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Structural transformations produced in strain‐relaxed, low‐dislocation‐density Si0.6Ge0.4 films by As+ implantation and rapid thermal annealing were studied by transmission electron microscopy and x‐ray microanalysis. The type of residual defects was found to be strongly dependent on annealing temperature. Only perfect dislocation loops were observed in implanted layers after annealing at 800 °C. Annealing at higher temperature (900 °C) results in complete removal of irradiation damage accompanied by the formation of GeAs precipitates of monoclinic phase and spherical shape. The results show that the behavior of As in Si–Ge alloys during thermal processing is remarkably different from that in Si. In particular, precipitation of As atoms in Si0.6Ge0.4 was found at an As concentration of 9×1020 cm−3 which is at least one order of magnitude lower than the critical As concentration for As precipitation in Si. © 1996 American Institute of Physics.
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61.72.Cc Kinetics of defect formation and annealing
61.72.up Other materials
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

AlGaAs/GaAs wire and box structures prepared by molecular‐beam epitaxial regrowth on in situ patterned GaAs substrates

M. López, N. Tanaka, I. Matsuyama, and T. Ishikawa

Appl. Phys. Lett. 68, 658 (1996); http://dx.doi.org/10.1063/1.116500 (3 pages) | Cited 7 times

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We have developed a processing technique which is conducted entirely under an ultrahigh vacuum environment, called in situ electron‐beam (EB) lithography, to pattern GaAs substrates on which AlGaAs/GaAs wire and box structures are subsequently regrown. In this technique a thin GaAs oxide layer is selectively formed by EB‐stimulated oxidation under a controlled oxygen atmosphere, and is then used as a mask material to define mesa stripes and mesa squares by Cl2 gas etching. Subsequently, the initial mesa size is reduced by the regrowth of a GaAs layer. Finally, AlGaAs/GaAs wire and box structures are fabricated on the top of the mesas by the growth of a quantum well. These structures were characterized by cathodoluminescence measurements at 77 K. © 1996 American Institute of Physics.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices

New amorphous semiconductor: 2CdO⋅PbOx

Hideo Hosono, Yasuhisa Yamashita, Naoyuki Ueda, Hiroshi Kawazoe, and Ken‐ichi Shimidzu

Appl. Phys. Lett. 68, 661 (1996); http://dx.doi.org/10.1063/1.116501 (3 pages) | Cited 17 times

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A new amorphous semiconductor, 2CdO⋅PbOx (band gap: 1.58 eV), was found. Thin films of this material were prepared by rf sputtering of a Cd2PbO4 target in O2–Ar. The dc conductivity of the resulting amorphous thin films was ∼180 S cm−1 at 300 K and remained almost constant down to ∼4 K. The concentration of carrier electrons and the Hall mobility in the as‐deposited state were 1×1020 cm−3 and 9 cm2 V−1 s−1, respectively. When the as‐deposited specimens were heated to 250 °C, which is far below the crystallization (to Cd2PbO4) temperature (460 °C), the conductivity and the carrier concentration at 300 K became approximately twice as high. The thermal O2‐desorption measurements demonstrated that carrier electrons are generated via the formation of oxygen vacancies at the initial stage (<250 °C) of thermal desorption of O2 from the amorphous structure. The effective mass of carrier electrons was estimated as 0.57m0. © 1996 American Institute of Physics.
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73.61.Jc Amorphous semiconductors; glasses
81.05.Gc Amorphous semiconductors
81.15.Cd Deposition by sputtering

Synthesis of epitaxial SnxGe1−x alloy films by ion‐assisted molecular beam epitaxy

Gang He and Harry A. Atwater

Appl. Phys. Lett. 68, 664 (1996); http://dx.doi.org/10.1063/1.116502 (3 pages) | Cited 30 times

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In this letter, we report the synthesis of epitaxial SnxGe1−x/Ge/Si(001) with compositions up to x=0.34 by ion‐assisted molecular beam epitaxy with 30–100 eV Ar+ ions produced by an electron cyclotron resonance ionization source with ion to atom flux ratios of the order of unity in the substrate temperature range of 120–200 °C. High flux low energy ion beam irradiation greatly inhibits Sn segregation without interrupting epitaxy. © 1996 American Institute of Physics.
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81.05.Hd Other semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Activation of acceptors in Mg‐doped GaN grown by metalorganic chemical vapor deposition

W. Götz, N. M. Johnson, J. Walker, D. P. Bour, and R. A. Street

Appl. Phys. Lett. 68, 667 (1996); http://dx.doi.org/10.1063/1.116503 (3 pages) | Cited 177 times

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The activation kinetics of acceptors was investigated for heteroepitaxial layers of GaN, doped with Mg. After growth, the samples were exposed to isochronal rapid thermal anneals in the temperature range from 500 to 775 °C. The samples were studied by variable temperature Hall effect measurements and photoluminescence (PL) spectroscopy in the as‐grown condition and after each temperature step. The thermal treatment reduced the resistivity by six orders of magnitude and the p‐type conductivity was found to be dominated by an acceptor with an activation energy of ∼170 meV. This acceptor is attributed to Mg atoms substituting for Ga in the GaN lattice and the activation process is consistent with dissociation of electrically inactive Mg–H complexes. It is shown that the appearance of a blue emission band in the PL spectrum of Mg‐doped GaN does not directly correlate with the increase in p‐type conductivity. © 1996 American Institute of Physics.
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61.72.uj III-V and II-VI semiconductors
71.55.Eq III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Effect of rapid thermal annealing on the electrical and physical properties of metalorganic chemical‐vapor‐deposited TiN

S. C. Sun and M. H. Tsai

Appl. Phys. Lett. 68, 670 (1996); http://dx.doi.org/10.1063/1.116586 (3 pages) | Cited 5 times

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This work reports on the effect of postdeposition thermal treatment using rapid thermal annealing on the physical and electrical properties of metalorganic chemical‐vapor‐deposited (MOCVD) titanium nitride (TiN) thin films. When ammonia is used as the annealing ambient, the resistivity decreases with increasing annealing temperature. The resistivity of MOCVD TiN was reduced from 6000 to 320 μΩ cm after 800 °C rapid thermal annealing in ammonia (RTN). Annealing in nitrogen ambient was found to be not nearly as effective as that in ammonia. The decrease in resistivity may be attributed to a reduction in the carbon and oxygen content, growth in grain size through polycrystalline recrystallization, as well as to an increase in film density. © 1995 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
81.40.Rs Electrical and magnetic properties related to treatment conditions

Temperature‐dependent generation of misfit dislocations in In0.2Ga0.8As/GaAs single heterostructures

J. Zou, D. J. H. Cockayne, and B. F. Usher

Appl. Phys. Lett. 68, 673 (1996); http://dx.doi.org/10.1063/1.116587 (2 pages) | Cited 8 times

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The onset of misfit dislocation generation in [001] In0.2Ga0.8As/GaAs single heterostructures is investigated by transmission electron microscopy using the liftoff technique. To determine the equilibrium critical thickness of misfit dislocation generation for different temperatures, postgrowth annealing was carried out for 2 h at 530 and 600 °C. The equilibrium critical thicknesses are determined as 100–120 Å for 530 °C postgrowth annealing and 60–80 Å for 600 °C postgrowth annealing, respectively. Metastable dislocation structures can be disturbed by sustained elevated temperatures. The variability in the effect is once again due to variations in the extent of dislocation pinning. © 1996 American Institute of Physics.
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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.

The forward biased junction: a sensitive detector for far‐infrared radiation

M. López Sáenz and J. M. Guerra Pérez

Appl. Phys. Lett. 68, 675 (1996); http://dx.doi.org/10.1063/1.116588 (3 pages) | Cited 3 times

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The strong bias dependence of the far‐infrared laser‐induced negative photoeffect is here attributed to an intrinsic bias dependent internal photoemission effect. Experimental results fit remarkably well with the carrier temperature and the transition potential predicted by our model. We demonstrate that any asymmetric heavily doped junction (P+/N, N+/P) which is properly forward biased is suitable to detect far infrared radiation. The sensitivity is reasonable (≊1 mV per kW at 300 K) for detection of pulsed radiation and the rise time is intrinsically fast (≤1 ns). © 1996 American Institute of Physics.
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07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
72.40.+w Photoconduction and photovoltaic effects

Electron energy loss in thin metallic films

C. R. K. Marrian, F. K. Perkins, D. McCarthy, and R. Bass

Appl. Phys. Lett. 68, 678 (1996); http://dx.doi.org/10.1063/1.116589 (3 pages) | Cited 3 times

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Schottky diodes with patterned overlayers of thin metal films have provided a method to measure the energy loss of high energy electrons in the metal films. The technique avoids the problems of surface contamination and electron collection which complicate measurements on freestanding films. The patterned overlayer creates a modulation in the reverse biased diode current as a beam of focused electrons is moved across the diode surface. The amplitude of the modulation has been measured with overlayers of aluminum and gold for incident electron energies of 5 to 30 keV. The results have been compared to that predicted from a Monte Carlo calculation of the inelastic and elastic scattering of the incident electrons. Significantly better agreement between experiment and simulation is observed when the screened Rutherford cross section in the Monte Carlo code is replaced by an empirical expression for the Mott scattering formula. © 1996 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
78.70.-g Interactions of particles and radiation with matter

Epitaxial quality of thin Ag films on GaAs(100) surfaces cleaned with various wet etching techniques

K. E. Mello, S. R. Soss, S. P. Murarka, T.‐M. Lu, and S. L. Lee

Appl. Phys. Lett. 68, 681 (1996); http://dx.doi.org/10.1063/1.116590 (3 pages) | Cited 5 times

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2θ and pole figure x‐ray analysis have been used to examine the crystal structure and orientation of Ag films deposited on GaAs(100) substrates cleaned by a variety of wet etches. Where epitaxy was observed, it was of the type Ag(110)/GaAs(100). The H3PO4/HCl sequential etch yielded the film with the highest degree of preferred orientation, with the H2SO4/HCl, NH4OH, and HF etches producing films of decreasing quality in the order named. The epitaxial quality is thought to scale with elemental As concentration on the GaAs(100) surface, and have an inverse relationship to the amount of surface oxides present before deposition. © 1996 American Institute of Physics.
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81.05.Bx Metals, semimetals, and alloys
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Visible electroluminescence from porous silicon/hydrogenated amorphous silicon pn‐heterojunction devices

Peter C. Sercel, Daewon Kwon, Teha Vilbrandt, Weidong Yang, John Hautala, J. David Cohen, and Hao Lee

Appl. Phys. Lett. 68, 684 (1996); http://dx.doi.org/10.1063/1.116591 (3 pages) | Cited 3 times

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We report the fabrication and characterization of a p‐type porous silicon/ n‐type hydrogenated amorphous silicon (a‐Si:H) pn‐heterojunction electroluminescent device structure. The devices exhibit electroluminescence in forward bias, demonstrating minority carrier injection from n‐type a‐Si:H into p‐type porous silicon. © 1996 American Institute of Physics.
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78.60.Fi Electroluminescence
85.60.Jb Light-emitting devices

Current transport in free‐standing porous silicon

A. Diligenti, A. Nannini, G. Pennelli, and F. Pieri

Appl. Phys. Lett. 68, 687 (1996); http://dx.doi.org/10.1063/1.116592 (3 pages) | Cited 20 times

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The electrical conduction of free‐standing porous silicon layers, obtained from n+ silicon with various anodization currents and illumination conditions, has been investigated in vacuum as a function of the temperature in the interval 300‐210 K. The two‐contact I‐V characteristic is determined by the metal/porous silicon rectifying interface, whereas, by using the four‐contact technique, a linear dependence of the current vs voltage was found. The resistance of free‐standing samples showed a thermally activated behavior, with activation energies ranging from 0.1 to 0.44 eV. It was found that the activation energy decreased if the light intensity during the anodization was reduced. Variations of activation energy were also observed if the anodization current was changed but, in this case, it was not possible to find any correlation over the parameter range investigated. © 1996 American Institute of Physics.
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73.50.Pz Photoconduction and photovoltaic effects
73.63.-b Electronic transport in nanoscale materials and structures

Qualitative model for the fatigue‐free behavior of SrBi2Ta2O9

H. N. Al‐Shareef, D. Dimos, T. J. Boyle, W. L. Warren, and B. A. Tuttle

Appl. Phys. Lett. 68, 690 (1996); http://dx.doi.org/10.1063/1.116593 (3 pages) | Cited 124 times

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SrBi2Ta2O9 (SBT) thin films are known to exhibit no polarization fatigue with electric field cycling. However, we have discovered that optical illumination combined with a bias voltage near the switching threshold can result in significant (≳90%) suppression of the switchable polarization of SBT thin film capacitors. A similar effect has also been reported for Pb(ZrxTi1−x)O3 (PZT) capacitors. However, it is found that electric field cycling of the optically fatigued SBT capacitors results in near‐complete recovery of the suppressed polarization. In contrast, electric field cycling of optically fatigued PZT capacitors does not result in any polarization recovery. These results suggest that optical fatigue in both SBT and PZT capacitors results from pinning of domain walls due to trapping of the photogenerated carriers at domain boundaries, whereas the recovery exhibited by SBT thin films indicates that the domain walls are more weakly pinned in SBT than in PZT thin films. Consequently, the fatigue‐free behavior of SBT thin films during electric field cycling can be viewed as a competition between domain wall pinning due to charge trapping and domain wall unpinning by the cycling field; the latter process occurring at least as rapidly as the former. © 1996 American Institute of Physics.
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77.80.Fm Switching phenomena
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
84.32.Tt Capacitors

Characterization of surface imperfections of silicon‐on‐insulator wafers by means of extremely asymmetric x‐ray reflection topography

Shigeru Kimura, Atsushi Ogura, and Tetsuya Ishikawa

Appl. Phys. Lett. 68, 693 (1996); http://dx.doi.org/10.1063/1.116594 (3 pages) | Cited 3 times

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Surface imperfections of silicon‐on‐insulator (SOI) wafers are investigated by means of extremely asymmetric x‐ray reflection topography, in which the glancing angle of the incident x rays is near the critical angle of total reflection; this geometry is achieved by using tunable wavelength synchrotron radiation. Two kinds of SOI wafers: bonded and two oxygen implanted silicon wafers are used as samples. The experimental topographs reveal a characteristic contrast for each sample, which cannot be observed by conventional x‐ray topography. The observed contrasts strongly depend on the fabrication techniques of the SOI wafers. © 1996 American Institute of Physics.
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61.05.cm X-ray reflectometry (surfaces, interfaces, films)
68.35.B- Structure of clean surfaces (and surface reconstruction)

Alloy composition dependence of photoexcited carrier dynamics in GaxIn1−xP/InP:Fe (x<0.18)

Y.‐G. Zhao, R. Jing, Y.‐H. Zou, Z.‐J. Xia, X.‐L. Huang, W.‐X. Chen, and R. A. Masut

Appl. Phys. Lett. 68, 696 (1996); http://dx.doi.org/10.1063/1.116595 (3 pages) | Cited 6 times

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We have observed the reflection recovery dynamics of photoexcited GaxIn1−xP/InP:Fe (x<0.18), using the pump‐probe technique, and found that the delay time of the reflection recovery dynamics increases with increasing gallium composition. To understand the experimental results, we have also performed a simulation study, which is in good agreement with the measured data, and shows that ambipolar diffusion plays a dominant role in determining the photoexcited carrier dynamics. © 1996 American Institute of Physics.
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73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
78.47.-p Spectroscopy of solid state dynamics
78.66.Fd III-V semiconductors

Electrical characterization of low‐temperature Al0.3Ga0.7As using n‐i‐n structures

A. K. Verma, J. Tu, J. S. Smith, H. Fujioka, and E. R. Weber

Appl. Phys. Lett. 68, 699 (1996); http://dx.doi.org/10.1063/1.116596 (3 pages) | Cited 2 times

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Through temperature‐dependent conductivity measurements, we show evidence of a deep trap level in low‐temperature (LT) Al0.3Ga0.7As layers with an activation energy of ∼0.96 eV. This energy is near that of EL2‐like defects found previously in ‘‘normal’’ epitaxial Al0.3Ga0.7As. It is also considerably larger than the 0.70 eV value typically associated with defects in LT GaAs, which may explain the observed large resistivity (≳1011 Ω cm) in LT Al0.3Ga0.7As. Current transient spectroscopy (CTS) of these samples yields a deep level activation energy of 1.01 eV, in close agreement with the value obtained from conductivity measurements. © 1996 American Institute of Physics.
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71.55.Eq III-V semiconductors
73.61.Ey III-V semiconductors

High quality Nb/Al–AlOx/Nb superconducting tunnel junctions for radiation detection

K. Joosse, H. Nakagawa, H. Akoh, S. Takada, K. Maehata, and K. Ishibashi

Appl. Phys. Lett. 68, 702 (1996); http://dx.doi.org/10.1063/1.116597 (3 pages) | Cited 7 times

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Nb/Al–AlOx/Nb tunnel junctions designed for x‐ray detection have been manufactured and characterized at temperatures down to 0.35 K. At a bias voltage of 0.5 mV, a leakage current of the order of 0.1 pA/μm2, and a dynamic resistance exceeding 106 times the normal state resistance, were achieved in junctions with dimensions up to 200×200 μm2 and critical current densities of order 200 A/cm2. The combination of high critical current density, low leakage current, and large area represents an important step towards the development of superconducting tunnel junction detectors with improved spectroscopic performance. © 1996 American Institute of Physics.
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07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
85.25.Cp Josephson devices

Microwave power dependence of YBa2Cu3O7 thin‐film Josephson edge junctions

D. E. Oates, P. P. Nguyen, Y. Habib, G. Dresselhaus, M. S. Dresselhaus, G. Koren, and E. Polturak

Appl. Phys. Lett. 68, 705 (1996); http://dx.doi.org/10.1063/1.116598 (3 pages) | Cited 26 times

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Using a stripline resonator technique, we measured the dependence on microwave current of the impedance of fabricated superconductor/normal‐metal/superconductor Josephson junctions in YBa2Cu3O7 thin films. The results are compared with predictions of a resistively shunted junction model that yields good agreement at low and intermediate values of the microwave current. At high currents deviations from the model predictions are observed, which we propose are due to flux penetration into the junction. The results are consistent with previously proposed explanations of the rf power dependence of the high‐Tc materials. © 1996 American Institute of Physics.
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74.25.N- Response to electromagnetic fields
74.50.+r Tunneling phenomena; Josephson effects
85.25.Cp Josephson devices

Current resolution, noise, and inductance measurements on high‐Tc dc SQUID galvanometers

E. Il’ichev, L. Dörrer, F. Schmidl, V. Zakosarenko, P. Seidel, and G. Hildebrandt

Appl. Phys. Lett. 68, 708 (1996); http://dx.doi.org/10.1063/1.116599 (3 pages) | Cited 15 times

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Single layer autonomous high‐Tc dc superconducting quantum interference devices (SQUIDs) have been fabricated and tested. The SQUIDs were designed for application as a galvanometer. The current to be measured is injected directly in a microstrip segment of the SQUID loop. Step‐edge as well as bicrystal YBCO Josephson junctions were used. We consider two aspects: (i) optimization of the noise properties with respect to current resolution, and (ii) temperature dependence of the period of voltage‐flux relation. The SQUID inductance was calculated numerically taking into account the magnetic field penetration depth λ. The temperature dependence of λ(T) was obtained from experimental results and is found to be in good agreement with λ(T)≊λ(0)[1−(T/TC)2]−1/2. © 1996 American Institute of Physics.
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07.55.-w Magnetic instruments and components
85.25.Dq Superconducting quantum interference devices (SQUIDs)

Effect of texture on grain boundary misorientation distributions in polycrystalline high temperature superconductors

A. Goyal, E. D. Specht, D. M. Kroeger, and T. A. Mason

Appl. Phys. Lett. 68, 711 (1996); http://dx.doi.org/10.1063/1.116600 (3 pages) | Cited 14 times

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Computer simulations were performed to determine the most probable grain boundary misorientation distribution (GBMD) in model polycrystalline superconductors. GBMDs in polycrystalline superconductors can be expected to dictate the macroscopic transport critical current density, Jc. Calculations were performed by simulating model polycrystals and then determining the GBMD. Such distributions were calculated for random materials having cubic, tetragonal, and orthorhombic crystal symmetry. In addition, since most high temperature superconductors are tetragonal or pseudotetragonal, the effect of macroscopic uniaxial and biaxial grain orientation texture on the GBMD was determined for tetragonal materials. It is found that macroscopic texture drastically alters the grain boundary misorientation distribution. The fraction of low angle boundaries increases significantly with uniaxial and biaxial texture. The results of this study are important in correlating the macroscopic transport Jc with the measured grain orientation texture as determined by x‐ray diffraction © 1996 American Institute of Physics.
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61.72.Mm Grain and twin boundaries
74.72.-h Cuprate superconductors
74.81.Bd Granular, melt-textured, amorphous, and composite superconductors

Structure and magnetic properties of epitaxial spinel ferrite thin films

Y. Suzuki, R. B. van Dover, E. M. Gyorgy, Julia M. Phillips, V. Korenivski, D. J. Werder, C. H. Chen, R. J. Cava, J. J. Krajewski, W. F. Peck, and K. B. Do

Appl. Phys. Lett. 68, 714 (1996); http://dx.doi.org/10.1063/1.116601 (3 pages) | Cited 72 times

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We have grown epitaxial spinel ferrite thin films of (Mn,Zn) Fe2O4 and CoFe2O4 on (100) and (110) SrTiO3 and MgAl2O4 buffered by spinel structure buffer layers. High quality spinel ferrite films were grown at 400 °C on buffer layers that were grown at 600 °C and postannealed at 1000 °C. Although (Mn,Zn) Fe2O4 grown directly on SrTiO3 and MgAl2O4 shows mediocre structural and magnetic properties, ferrite films grown on (100) and (110) SrTiO3 and MgAl2O4 buffered with CoCr2O4 exhibit excellent crystallinity and bulk saturation magnetization values, thus indicating the importance of lattice match and structural similarity between the film and the immediately underlying layer. © 1996 American Institute of Physics.
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75.50.Gg Ferrimagnetics
75.70.-i Magnetic properties of thin films, surfaces, and interfaces
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Scanning force microscopy measurements of latent image topography in chemically amplified resists

L. E. Ocola, D. S. Fryer, G. Reynolds, A. Krasnoperova, and F. Cerrina

Appl. Phys. Lett. 68, 717 (1996); http://dx.doi.org/10.1063/1.116602 (3 pages) | Cited 14 times

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Noncontact scanning force microscopy topography measurements of exposed and undeveloped photoresists are reported. A negative chemically amplified photoresist, SAL605, was patterned by electron beam direct writing of 1 μm line linear gratings, and 5 mm pads. A relief image of exposed unbaked resist has been observed of the order of a few Å, and then monitored as a function of time after exposure. This relief image undergoes a topography transformation with postexposure bake (PEB), yielding a ridge located at the exposed–unexposed region interface, extending several nanometers in vertical and about one micrometer laterally. The effect has been investigated as a function of PEB time and exposure dose. Correlations of the observed phenomena with optical film thickness monitoring techniques and previously reported data on the photoresist chemical changes during exposure and PEB are discussed. Two independent mechanisms contributing to the image formation are identified. The data show that the local chemistry of the latent image at the edges of feature is different than in wider features. This has important implications for the application of chemically amplified resists to high‐resolution lithography. © 1996 American Institute of Physics.
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68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
68.60.-p Physical properties of thin films, nonelectronic
85.40.Hp Lithography, masks and pattern transfer

Field emission from silicon and molybdenum tips coated with diamond powder by dielectrophoresis

W. B. Choi, J. J. Cuomo, V. V. Zhirnov, A. F. Myers, and J. J. Hren

Appl. Phys. Lett. 68, 720 (1996); http://dx.doi.org/10.1063/1.116585 (3 pages) | Cited 44 times

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Thin diamond layers have been formed on molybdenum and single‐crystal silicon field emitters using a dielectrophoresis coating method from a suspension of diamond powder in a nonconducting fluid. Transmission and scanning electron microscopy observation revealed a significant amount of diamond on the tips. The average thickness of the deposited diamond layer depended on the applied bias and the immersion time. Field emission from these diamond‐coated emitters exhibited significant enhancement compared to the pure emitters. © 1996 American Institute of Physics.
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79.70.+q Field emission, ionization, evaporation, and desorption
81.15.Pq Electrodeposition, electroplating
FREE

Erratum: ‘‘Enhancement of second harmonic generation at 1.06 μm using a quasi‐phase‐matched AlGaAs/GaAs asymmetric quantum well structure’’ [Appl. Phys. Lett. 65, 3176 (1994)]

Xiaohua H. Qu, Harry Ruda, Siegfried Janz, and Anthony J. SpringThorpe

Appl. Phys. Lett. 68, 723 (1996); http://dx.doi.org/10.1063/1.116795 (1 page)

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Abstract Unavailable
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42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
78.66.Fd III-V semiconductors
99.10.Cd Errata
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