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28 Aug 1995

Volume 67, Issue 9, pp. 1179-1334

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Ultraviolet dosimetry using thermoluminescence of semiconductor‐doped Vycor glass

Brian L. Justus and Alan L. Huston

Appl. Phys. Lett. 67, 1179 (1995); http://dx.doi.org/10.1063/1.114999 (3 pages) | Cited 6 times

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Radiation dosimetry in the ultraviolet is described using the intrinsic ultraviolet response of a novel thermoluminescent semiconductor‐doped Vycor glass. A linear response to 185 nm light was measured over the range 0.1 to 1000 μJ/cm2. The long wavelength limit of the sensitivity of the glass is ∼290 nm, indicating the utility of the glass as an effective solar blind dosimeter. © 1995 American Institute of Physics.
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07.60.Dq Photometers, radiometers, and colorimeters
87.80.-y Biophysical techniques (research methods)
78.60.Kn Thermoluminescence

The influence of aluminum concentration on photoelectrochemical etching of first order gratings in GaAs/AlGaAs

Elizabeth J. Twyford, Carrie A. Carter, Paul A. Kohl, and Nan Marie Jokerst

Appl. Phys. Lett. 67, 1182 (1995); http://dx.doi.org/10.1063/1.115000 (3 pages) | Cited 1 time

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We present a set of experiments which systematically clarifies the enhancement of photoelectrochemical (PEC) etching due to the mole fraction of aluminum in AlxGa1−xAs. The spatial resolution of gratings etched in Al0.3Ga0.7As is as much as three times greater than the spatial resolution of gratings etched in GaAs, so that the smallest practical grating period is about 0.3 μm, as compared with about 0.7 μm using previous techniques. This technique enabled PEC fabrication of first order gratings for waveguide outcouplers. The lower hole mobility of AlxGa1−xAs is proposed as a possible explanation for this grating resolution improvement. © 1995 American Institute of Physics.  
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81.65.-b Surface treatments
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
82.45.-h Electrochemistry and electrophoresis

Direct visualization of electromagnetic microfields by interference of three electron waves

Tsukasa Hirayama, Takayoshi Tanji, and Akira Tonomura

Appl. Phys. Lett. 67, 1185 (1995); http://dx.doi.org/10.1063/1.115001 (3 pages) | Cited 3 times

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A method is presented for direct visualization of electromagnetic microfields. Using a transmission electron microscope equipped with a field‐emission electron gun and two electron biprisms, an object wave and two reference waves are superposed to interfere for producing a new type of interference pattern in which electromagnetic fields are directly observed. Equal‐potential lines of an electric field around a latex particle and magnetic flux lines emerging from a barium ferrite particle have been observed. © 1995 American Institute of Physics.
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07.68.+m Photography, photographic instruments; xerography
07.55.Ge Magnetometers for magnetic field measurements

Techniques for neutron diffraction on solidified gases to 10 GPa and above: Applications to ND3 phase IV

S. Klotz, M. Gauthier, J. M. Besson, G. Hamel, R. J. Nelmes, J. S. Loveday, R. M. Wilson, and W. G. Marshall

Appl. Phys. Lett. 67, 1188 (1995); http://dx.doi.org/10.1063/1.115002 (3 pages) | Cited 20 times

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Neutron powder diffraction can provide important structural information on hydrogenous compounds which are gases at ambient temperature. For high pressure studies, however, this technique has been seriously limited by the fact that it was impossible (a) to load such gases in large volume devices and (b) to compress them to elevated pressures above some 1 GPa. In this letter we show that, using a previously described pressure cell, a wide range of gaseous samples may be loaded and compressed to ∼10 GPa with standard tungsten carbide anvils. We illustrate the effectiveness of the technique with neutron powder diffraction data recently collected on deuterated ammonia ND3 phase IV, where accurate structural data were obtained after a few hours collection time. © 1995 American Institute of Physics.
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61.05.fm Neutron diffraction
62.50.-p High-pressure effects in solids and liquids
64.10.+h General theory of equations of state and phase equilibria
64.30.-t Equations of state of specific substances

Second harmonic generation and atomic‐force microscopy studies of porous silicon

O. A. Aktsipetrov, A. V. Melnikov, Yu. N. Moiseev, T. V. Murzina, C. W. van Hasselt, Th. Rasing, and G. Rikken

Appl. Phys. Lett. 67, 1191 (1995); http://dx.doi.org/10.1063/1.115003 (3 pages) | Cited 4 times

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Structural properties of porous silicon were studied with atomic‐force microscopy (AFM) and optical second harmonic generation (SHG). Depending on etching conditions, the SHG response was observed to be either anisotropic, showing C2v symmetry, or isotropic. This correlated with AFM observations of quasi ordered structures in the first case. The Si etching process was studied by in situ SHG measurements. © 1995 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
81.65.-b Surface treatments
68.35.B- Structure of clean surfaces (and surface reconstruction)

Damage threshold for ion‐beam induced graphitization of diamond

C. Uzan‐Saguy, C. Cytermann, R. Brener, V. Richter, M. Shaanan, and R. Kalish

Appl. Phys. Lett. 67, 1194 (1995); http://dx.doi.org/10.1063/1.115004 (3 pages) | Cited 111 times

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The critical dose for graphitization of diamond as a result of ion implantation induced damage (boron and arsenic) and subsequent thermal annealing is determined by combining secondary ion mass spectroscopy measurements, chemical etching of the graphitized layer, and TRIM simulations. Li ions are implanted as a deep marker to accurately determine the position of the graphite/diamond interface. The damage density threshold, beyond which graphitization occurs upon annealing, is found to be 1022 vacancies/cm3. This value is checked against published data and is shown to be of general nature, independent of ion species or implantation energy. © 1995 American Institute of Physics.
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61.80.Jh Ion radiation effects
61.72.Cc Kinetics of defect formation and annealing

Diamond epitaxy on (001) silicon: An interface investigation

X. Jiang and C. L. Jia

Appl. Phys. Lett. 67, 1197 (1995); http://dx.doi.org/10.1063/1.115005 (3 pages) | Cited 60 times

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In combination with scanning electron microscopy and x‐ray pole‐figure analysis high resolution electron microscope (HREM) observation of the diamond‐silicon cross section in a 〈001〉 epitaxially oriented diamond film was carried out to investigate the atomic interfacial microstructure. The films were prepared by microwave plasma chemical vapor deposition using a bias‐enhanced nucleation technique. Due to the multiple fit of diamond and silicon lattices, there is a periodic 3‐to‐2 registry of {111} atom planes of the epitaxial diamond‐silicon interface. Planar defects on diamond {111} planes and interface misfit dislocations are shown for epitaxially oriented and for slightly misoriented diamond crystallites. A cubic silicon carbide ‘‘transition’’ is found to be unnecessary for the epitaxy. The misorientation of the grown crystallites is also studied and found to be probably due to interface imperfection. © 1995 American Institute of Physics.
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68.55.-a Thin film structure and morphology

Stress induced Li‐Li pairs reorientation in Al‐Li alloys

J. I. Pérez‐Landazábal, J. San Juan, and M. L. Nó

Appl. Phys. Lett. 67, 1200 (1995); http://dx.doi.org/10.1063/1.115006 (3 pages) | Cited 2 times

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Internal friction measurements have been performed in order to study the Li mobility in Al‐Li alloys. Coherent δ′ precipitation (nonequilibrium diffusion process) promotes a low temperature background increase according to Schoeck’s theory. A stable Pz relaxation has been observed at around 460 K (∼1 Hz). The analysis of the behaviour of this relaxation allows us to identify the Pz peak with the Zener relaxation associated to the stress induced Li‐Li pairs reorientation. The relaxation parameters lead us to determine the activation energy and the diffusion coefficient of Li. Zener relaxation has been observed in Al‐Li alloys. © 1995 American Institute of Physics.
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66.30.Fq Self-diffusion in metals, semimetals, and alloys
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances

A novel method for determining thin film density by energy‐dispersive x‐ray reflectivity

W. E. Wallace and W. L. Wu

Appl. Phys. Lett. 67, 1203 (1995); http://dx.doi.org/10.1063/1.115007 (3 pages) | Cited 16 times

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A technique utilizing the reflection of x‐rays to determine material density at flat surfaces is described. The effects of sample misalignment limit the accuracy of x‐ray reflectivity as typically practiced. These effects may be properly accounted for by measuring the critical angle for reflection at many different x‐ray wavelengths simultaneously from which an extrapolation of the position of the critical angle at infinite wavelength may be made. This extrapolation has the effect of correcting for sample misalignment. Use of the technique is demonstrated for single‐crystal silicon surfaces and for silica spin‐on‐glass thin films. © 1995 American Institute of Physics.
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78.70.Ck X-ray scattering
68.60.Wm Other nonelectronic physical properties
07.85.-m X- and γ-ray instruments

Estimation of the depth resolution of secondary ion mass spectrometry at the interface SiO2/Si

J. Kocanda, V. Fesič, M. Veselý, J. Breza, and M. Kadlečíková

Appl. Phys. Lett. 67, 1206 (1995); http://dx.doi.org/10.1063/1.115008 (2 pages)

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Similarities between the processes that occur during sputtering of monocrystalline Si by reactive O2+ primary ions and the interface SiO2/monocrystalline Si by noble gas ions (e.g., by Ar+) have motivated us to utilize the semiempirical model of P. C. Zalm and C. J. Vriezema [Nucl. Instrum. Methods B 67, 495 (1992)], modified later by M. Petravić, B. G. Svensson, and J. S. Williams [Appl. Phys. Lett. 62, 278 (1993)] to calculate the decay length λb, as defined by J. B. Clegg [Surf. Interface Anal. 10, 322 (1987)], at the SiO2/Si interface. The measured and calculated results agree remarkably well. Inconsistency observed to be larger than 100% for glancing incidence angles confirms limitations of this model that were admitted already by its authors. © 1995 American Institute of Physics.
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
81.65.-b Surface treatments
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Growth model for PbTiO3 thin films grown by surface‐reaction enhanced metalorganic chemical vapor deposition

Atsushi Yamashita and Toru Tatsumi

Appl. Phys. Lett. 67, 1208 (1995); http://dx.doi.org/10.1063/1.115009 (3 pages) | Cited 3 times

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PbTiO3 thin films were prepared by surface‐reaction enhanced metalorganic chemical vapor deposition. The deposition rate was limited by supply of a Ti precursor. In contrast, the deposition rate and composition were kept constant for a certain range of Pb‐source feeding, although the deposition rate of PbTiO3 was lower than that of TiO2. From these results, we proposed a growth model for PbTiO3: stoichiometric PbTiO3 film is grown by the Ti species arriving and reacting on the Pb‐covered surface. The Ti sticking coefficient is rather small on such a surface. This model qualitatively explains the change in step coverage. © 1995 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates

Transient dielectric study of bistable reflective cholesteric displays and design of rapid drive scheme

Xiao‐Yang Huang, Deng‐Ke Yang, and J. William Doane

Appl. Phys. Lett. 67, 1211 (1995); http://dx.doi.org/10.1063/1.115010 (3 pages) | Cited 15 times

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Transient dielectric measurement is used to study the transitions among the planar, focal conic, and homeotropic states of cholesteric liquid crystals. If the initial state is the field‐induced homeotropic state, at low bias fields, the liquid crystal transforms to the planar state in a sequence of homeotropic‐transient planar–planar; at high bias fields, the liquid crystal transforms to the focal conic state. The homeotropic‐transient planar transition is on the order of 1 ms while the homeotropic‐focal conic transition is on the order of 100 ms. Large hysteresis is observed in the transitions between the homeotropic and the focal conic state. Based on the rapid homeotropic‐transient planar transition and the hysteresis effect in the focal conic‐homeotropic transition, we have designed a drive scheme which can address bistable reflective cholesteric displays at the speed of one line per millisecond. © 1995 American Institute of Physics.
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61.30.-v Liquid crystals
42.70.Df Liquid crystals
42.79.Kr Display devices, liquid-crystal devices

Synthesis of nanosize powders of alumina by ablation plasma produced by intense pulsed light‐ion beam

K. Yatsui, C. Grigoriu, H. Kubo, K. Masugata, and Y. Shimotori

Appl. Phys. Lett. 67, 1214 (1995); http://dx.doi.org/10.1063/1.115011 (3 pages) | Cited 21 times

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Nanosize powders of alumina have been synthesized by high‐density ablation plasma produced by the irradiation of an intense, pulsed, light‐ion beam on an aluminum target in oxygen. Diameters of the powders, which are observed to be spherical, are typically 5–25 nm. At 1 Torr of oxygen, nanosize powders of aluminum are synthesized with those of a small amount of γ‐alumina. At 10 Torr of oxygen, on the other hand, γ‐alumina powders are produced with a small amount of aluminum powders. Annealing characteristics in nitrogen have also been studied on the transition from γ‐ to α‐alumina. © 1995 American Institute of Physics.
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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
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation

Variation of the thermovoltage across a vacuum tunneling barrier: Copper islands on Ag(111)

A. Rettenberger, C. Baur, K. Läuger, D. Hoffmann, J. Y. Grand, and R. Möller

Appl. Phys. Lett. 67, 1217 (1995); http://dx.doi.org/10.1063/1.115012 (3 pages) | Cited 8 times

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If there is a temperature difference between tip and sample of a scanning tunneling microscope a thermovoltage is generated which is very sensitive to the electronic states involved in the tunneling process. This has been used, e.g., to distinguish between different metals of a heterogeneous metallic surface. To demonstrate the capability of this method it has been applied to copper islands on a Ag(111) surface. Knowing the thermopower for chemically homogeneous silver and copper surfaces of −45 and −15 μV/K, respectively, islands of copper on the silver substrate can be well identified with a lateral resolution of 1 nm. © 1995 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
68.35.B- Structure of clean surfaces (and surface reconstruction)

Characteristics of longitudinal optical phonon assisted quantum carrier capture process‐temperature and bias dependence

Ta‐Chung Wu, Sidney C. Kan, Dan Vassilovski, and Kam Y. Lau

Appl. Phys. Lett. 67, 1220 (1995); http://dx.doi.org/10.1063/1.115013 (3 pages)

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The quantum carrier capture time in a quantum well laser is calculated as a function of temperature and bias current. The calculated results show good consistency with recent measurements on the small signal frequency response of a quantum well laser at cryogenic temperatures. This calculation reveals some of the characteristics of longitudinal optical phonon assisted quantum carrier capture phenomena in quantum well structures. © 1995 American Institute of Physics.
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42.55.Px Semiconductor lasers; laser diodes
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

The dependence of ultrashallow junction depths on impact dose rates

A. Sultan, M. Craig, K. Reddy, S. Banerjee, E. Ishida, P. Maillot, T. Neil, and L. Larson

Appl. Phys. Lett. 67, 1223 (1995); http://dx.doi.org/10.1063/1.115014 (3 pages) | Cited 5 times

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Ultrashallow junctions (∼60 nm) are obtained using low energy BF2 (5 keV) implants in crystalline Si. The variation of junction depth as a function of the dose rate is studied for doses of 1×1014 and 1×1015 cm−2. Boron diffusion is retarded in the tail region for the higher dose rates and consequently the junction depth decreases as compared to the lower dose rates. The residual defect density after a 950 °C, 10 s anneal for a dose of 1×1015 cm−2 is reduced for the higher dose rate as compared to the lower dose rate. © 1995 American Institute of Physics.
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85.40.Hp Lithography, masks and pattern transfer
61.80.Jh Ion radiation effects
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Critical current‐length product for electromigration induced resistance changes in short Al lines

J. R. Kraayeveld, A. H. Verbruggen, A. W.‐J. Willemsen, and S. Radelaar

Appl. Phys. Lett. 67, 1226 (1995); http://dx.doi.org/10.1063/1.115015 (3 pages) | Cited 9 times

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Changes in the electrical resistance induced by electromigration in short (3–100 μm) pure Al lines show a rather well‐defined behavior. An applied dc current induces either an increase or a decrease of the resistance. For current densities below a critical value the resistance change saturates with time and the resistance fully recovers when the current is switched off. The length and temperature dependence of the resistance changes indicate that the observed time dependence is determined by grain boundary diffusion along the whole line length. Above the critical current density the resistance changes do not fully recover. Given the inevitable sample‐to‐sample variations, the product of the critical current density and the line length is constant. The value of this product is in good agreement with values of the constant product of threshold current density and line length found in drift velocity experiments. © 1995 American Institute of Physics.
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66.30.Qa Electromigration
61.72.Hh Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)

High‐speed (104 °C/s) scanning microcalorimetry with monolayer sensitivity (J/m2)

S. L. Lai, G. Ramanath, L. H. Allen, P. Infante, and Z. Ma

Appl. Phys. Lett. 67, 1229 (1995); http://dx.doi.org/10.1063/1.115016 (3 pages) | Cited 48 times

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We introduce a high sensitivity (1J/m2) scanning microcalorimeter that can be used at high heating rates (104 °C/s). The system is designed using ultrathin SiN membranes that serve as a low thermal mass mechanical support structure for the calorimeter. Calorimetry measurements of the system are accomplished via resistive heating techniques applied to a thin film Ni heating element that also serves as a thermometer. A current pulse through the Ni heater generates heat in the sample via Joule heating. The voltage and current characteristics of the heater were measured to obtain real‐time values of the temperature and the heat delivered to the system. This technique shows potential for measuring irreversible heat of reactions for processes at interfaces and surfaces. The method is demonstrated by measuring the heat of fusion for various amounts of thermally evaporated Sn ranging from 50 to 1000 Å. © 1995 American Institute of Physics.  
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07.20.-n Thermal instruments and apparatus
68.35.Md Surface thermodynamics, surface energies

Surface ripples, crosshatch pattern, and dislocation formation: Cooperating mechanisms in lattice mismatch relaxation

M. Albrecht, S. Christiansen, J. Michler, W. Dorsch, H. P. Strunk, P. O. Hansson, and E. Bauser

Appl. Phys. Lett. 67, 1232 (1995); http://dx.doi.org/10.1063/1.115017 (3 pages) | Cited 50 times

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We study the interplay of elastic and plastic strain relaxation of SiGe/Si(001). We show that the formation of crosshatch patterns is the result of a strain relaxation process that essentially consists of four subsequent stages: (i) elastic strain relaxation by surface ripple formation; (ii) nucleation of dislocations at the rim of the substrate followed by dislocation glide and deposition of a misfit dislocation at the interface; (iii) a locally enhanced growth rate at the strain relaxed surface above the misfit dislocations that results in ridge formation. These ridges then form a crosshatch pattern that relax strain elastically. (iv) Preferred nucleation and multiplication of dislocations in the troughs of the crosshatch pattern due to strain concentration. The preferred formation of dislocations again results in locally enhanced growth rates in the trough and thus leads to smoothing of the growth surface. © 1995 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.55.-a Thin film structure and morphology

Monte Carlo simulation of hot electron charge transport in diamond under an internal electric field

Z.‐H. Huang, M. S. Chung, P. H. Cutler, N. M. Miskovsky, and T. E. Sullivan

Appl. Phys. Lett. 67, 1235 (1995); http://dx.doi.org/10.1063/1.115018 (3 pages) | Cited 3 times

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Charge transport in diamond is studied using the Monte Carlo method, in which the scattering of electrons by phonons is considered stochastically. It is assumed that electrons are injected into the diamond conduction band with an initial equilibrium energy distribution and they are then accelerated by the internal field subject to phonon scattering. It is found that the electron energy distribution is independent of the field up to ≂0.1 V/μm. For larger fields, ‘‘hot’’ electron transport is predicted, i.e., the distribution shows a tail which depends on the internal field and the thickness of the diamond film. It implies that if electron field emission is from the conduction band in a diamond film, the transport and the energy spectrum of the emitted electrons should exhibit hot electron features. © 1995 American Institute of Physics.
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72.80.Cw Elemental semiconductors
79.70.+q Field emission, ionization, evaporation, and desorption

A novel technique for p‐type doping of ZnSe

A. A. El‐Emawy, Y. Qiu, A. Osinsky, E. Littlefield, and H. Temkin

Appl. Phys. Lett. 67, 1238 (1995); http://dx.doi.org/10.1063/1.115019 (3 pages) | Cited 1 time

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Thermally cracked nitric oxide (NO) has been used to grow heavily doped p‐type ZnSe layers. Net acceptor densities as high as ∼4×1018 cm−3 were obtained, as determined by capacitance–voltage profiling, in molecular beam epitaxial growth at 250 °C. Cracker efficiency as a function of temperature and the nitric oxide flow rate is discussed and correlated with the doping level in the epitaxial layer. © 1995 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.uj III-V and II-VI semiconductors

Optical switching mechanism based on charge accumulation effects in resonant tunneling diodes

Pyong Woon Park, Hye Yong Chu, Seon Gyu Han, Young Wan Choi, Gyungock Kim, and El‐Hang Lee

Appl. Phys. Lett. 67, 1241 (1995); http://dx.doi.org/10.1063/1.114384 (3 pages) | Cited 8 times

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We have identified the charge accumulation effects in a resonant tunneling diode for the application of optical switching by observing the hole tunneling peak under illumination with a Ti:sapphire laser. Two mechanisms, photocurrent and charge accumulation, are rigorously examined to determine which one is the dominant effect for optical switching by comparing the current–voltage (I–V) characteristics for forward biases and reverse biases. It is believed that the hole accumulation effect in the depletion region, which results in the hole tunneling current, is responsible for the shift of the I–V curves. © 1995 American Institute of Physics.
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73.40.Gk Tunneling
42.65.Pc Optical bistability, multistability, and switching, including local field effects
73.50.Pz Photoconduction and photovoltaic effects

The role of excess arsenic in interface mixing in low‐temperature‐grown AlAs/GaAs superlattices

I. Lahiri, D. D. Nolte, J. C. P. Chang, J. M. Woodall, and M. R. Melloch

Appl. Phys. Lett. 67, 1244 (1995); http://dx.doi.org/10.1063/1.114385 (3 pages) | Cited 20 times

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Undoped low‐temperature‐grown AlAs/GaAs superlattices experience pronounced interface intermixing with increasing anneal temperatures up to 900 °C. Quantum confinement shifts caused by intermixing of low‐temperature‐grown and standard‐temperature‐grown superlattices were studied using electromodulation spectroscopy. The effective activation energy for intermixing in the low‐temperature‐grown superlattices during 30 s isochronal postgrowth anneals was found to be (0.32±0.04) eV, anomalously smaller than for standard‐temperature‐grown superlattices. Roughening of the interfaces caused by arsenic precipitates accompanies the intermixing. Qualitative features of the intermixing have been confirmed using high resolution transmission electron microscopy and studies on x‐ray rocking curves. © 1995 American Institute of Physics.
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68.35.Fx Diffusion; interface formation
78.66.Fd III-V semiconductors

Growth of heteroepitaxial Si1−x−yGexCy alloys on silicon using novel deposition chemistry

Michael Todd, Philip Matsunaga, John Kouvetakis, D. Chandrasekhar, and David J. Smith

Appl. Phys. Lett. 67, 1247 (1995); http://dx.doi.org/10.1063/1.114386 (3 pages) | Cited 16 times

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We report heteroepitaxial growth of diamond‐structured Si1−x−yGexCy alloys on (100)Si substrates. Introduction of C into the diamond lattice is kinetically favored by low‐temperature (470 °C) interactions of C(SiH3)4, a novel C–H free carbon precursor, with mixtures of SiH4 and GeH4 using ultrahigh‐vacuum chemical vapor deposition techniques. Film thicknesses of 100 to 110 nm with 4–6 at. % C as indicated by Rutherford backscattering carbon resonance spectroscopy were obtained. Cross‐sectional transmission electron microscopy and Fourier transform infrared spectroscopy showed crystalline alloy phase formation with no detectable SiC precipitation. Secondary ion mass spectrometry revealed pure and highly homogeneous films. In situ annealing at 675 °C resulted in heteroepitaxial films with relatively few defects. © 1995 American Institute of Physics.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Study of chemically assisted ion beam etching of GaN using HCl gas

A. T. Ping, I. Adesida, and M. Asif Khan

Appl. Phys. Lett. 67, 1250 (1995); http://dx.doi.org/10.1063/1.114387 (3 pages) | Cited 43 times

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The use of an Ar ion beam and hydrogen chloride gas in the chemically assisted ion beam etching of GaN grown by metalorganic chemical vapor deposition is reported. Etch rates were investigated as a function of ion beam energy and substrate temperature. Hydrogen chloride gas was found to produce higher etch rates at lower ion beam energies (300 eV) and lower rates at higher energies (600 eV) in comparison to Cl2. Highly anisotropic etch profiles are demonstrated that indicate that the process may be suitable for the fabrication of laser facets and mirrors. Changes in surface stoichiometry resulting from the etching process were also investigated using Auger electron spectroscopy. © 1995 American Institute of Physics.
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81.65.-b Surface treatments
85.40.Hp Lithography, masks and pattern transfer
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