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28 Sep 1987

Volume 51, Issue 13, pp. 955-1045

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XeF laser at a high electron beam pump rate

A. Mandl and L. Litzenberger

Appl. Phys. Lett. 51, 955 (1987); http://dx.doi.org/10.1063/1.98774 (3 pages) | Cited 6 times

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A significant increase of the XeF laser efficiency has been observed in an electron beam pumped device. Mixtures of NF3, Xe, and Ne at 300 K and a density of 3 amagat were pumped at a rate of 300 kW/cm3 with a 500‐ns pulse. This deposited 150 J/l into the laser cavity. Measurements were made for various mixtures and output couplings. The highest intrinsic laser efficiency (defined as the ratio of laser output energy to e‐beam energy deposited into the gas) observed was 4.7%.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.-f Lasers

Theoretical evaluation of high‐efficiency operation of discharge‐pumped vacuum‐ultraviolet F2 lasers

Mieko Ohwa and Minoru Obara

Appl. Phys. Lett. 51, 958 (1987); http://dx.doi.org/10.1063/1.98775 (3 pages) | Cited 19 times

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We investigated theoretically the efficiency enhancement of discharge‐pumped vacuum‐ultraviolet F2 lasers using He/F2 mixtures in terms of the laser kinetics. As a result, the high mixture pressure is found to be essential for the high‐efficiency operation. Intrinsic efficiency in excess of 1% may be obtainable. Using a 6‐atm mixture of He/F2=98.5/0.15%, intrinsic efficiency of 1.5% may be obtainable with a specific output energy of 2.6 J/l.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Interfacing multispectral sensors to real time processors based on neural network models

K. M. S. V. Bandara, D. D. Coon, and R. P. G. Karunasiri

Appl. Phys. Lett. 51, 961 (1987); http://dx.doi.org/10.1063/1.98776 (3 pages) | Cited 2 times

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Experiments have been carried out to demonstrate and study the interfacing of silicon sensors to silicon devices which represent first stage elements of an artificial neural network. Sensor outputs (network inputs) are photocurrents associated with infrared, visible, or ultraviolet light. First stage linear coding of input current into the pulse rate of a stereotypical neuronlike spiketrain output has been achieved with a dynamic range of more than 106. For 1 pA inputs, the estimated noise referred to input is 10 fA. Network elements are shown to obey equations of the same form as equations which occur in nonlinear neural network models recently analyzed by Hopfield [Proc. Natl. Acad. Sci. 81, 3088 (1984)] and previously studied by Sejnowski [J. Math. Biology 4, 303 (1977)].
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85.60.Gz Photodetectors (including infrared and CCD detectors)
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
87.19.lt Sensory systems: visual, auditory, tactile, taste, and olfaction
42.79.Ta Optical computers, logic elements, interconnects, switches; neural networks

Mechanism of hydrocarbon formation upon interaction of energetic hydrogen ions with graphite

J. Roth and J. Bohdansky

Appl. Phys. Lett. 51, 964 (1987); http://dx.doi.org/10.1063/1.98777 (3 pages) | Cited 38 times

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The current model for hydrocarbon formation upon the interaction of energetic hydrogen ions with graphite assumes a reaction of adsorbed hydrogen with carbon surface atoms requiring a temperature of 800–900 K. This model is strongly questioned by results of hydrocarbon formation from a layered 13C/12C sample and by desorption measurements after room‐temperature implantation. The formation of 13CD4 and 12CD4 is monitored during deuterium bombardment of a pyrolytic graphite sample covered with a layer of 200 Å of 13C. Only for ion energies corresponding to ranges smaller than 200 Å 13CD4 dominates, while at higher energies only 12CD4 is found. The methane is thus formed at the end of ion range rather than in a surface reaction of back‐diffusing ions. Desorption experiments using a slow temperature range after room‐temperature implantation show the release of CD4 prior to D2, thus indicating a diffusion‐limited release of CD4 already formed during the implantation.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
34.50.Lf Chemical reactions

Nature of the self‐limiting effect in the low‐pressure chemical vapor deposition of tungsten

N. Lifshitz

Appl. Phys. Lett. 51, 967 (1987); http://dx.doi.org/10.1063/1.98778 (3 pages) | Cited 3 times

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We propose a mechanism for the self‐limiting effect which occurs in the low‐pressure chemical vapor deposition of tungsten. When W is deposited by silicon reduction of tungsten hexafluoride WF6, the deposition suddenly ceases at an early stage. No such effect is observed in the deposition of Mo using analogous chemistry. We believe the self‐limiting effect is due to the formation of nonvolatile lower fluorides of tungsten. Our hypothesis is supported by secondary ion mass spectroscopy studies which indicate the presence of fluorine (≊3%) in W films, whereas in Mo films the concentration of fluorine is an order of magnitude lower.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification

X‐ray study of a ferroelectric twin in poly(vinylidene fluoride)

N. Takahashi

Appl. Phys. Lett. 51, 970 (1987); http://dx.doi.org/10.1063/1.98779 (3 pages) | Cited 3 times

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A possibility for ferroelectric twinning of 60° domains existing in the phase‐I crystallite of poly(vinylidene fluoride) has been examined by the use of an x‐ray diffraction method. Interdomain interference causes anomalous splitting of the calculated diffraction peaks. Anomalous changes in the profiles are observed for the crystallites in a film under electric fields up to 120 MV/m, and can be explained in terms of the twin structure.
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77.80.Dj Domain structure; hysteresis
61.72.Mm Grain and twin boundaries
61.43.Fs Glasses
61.43.-j Disordered solids
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.

Depth profiles of defects in CdTe(100) overlayers grown by molecular beam epitaxy on GaAs(100)

E. Rauhala, J. Keinonen, K. Rakennus, and M. Pessa

Appl. Phys. Lett. 51, 973 (1987); http://dx.doi.org/10.1063/1.98780 (2 pages) | Cited 3 times

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The quality of crystal structure of CdTe(100) overlayers grown by molecular beam epitaxy on GaAs(100) substrates has been studied by x‐ray diffraction and Rutherford backscattering/channeling methods. The depth distribution of displaced atoms in the overlayers with thicknesses varying from 1.6 to 3.1 μm shows that a defect‐free surface is obtained when the film thickness is about 2 μm.
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68.55.-a Thin film structure and morphology
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.35.Dv Composition, segregation; defects and impurities

Role of Ostwald ripening in islanding processes

M. Zinke‐Allmang, L. C. Feldman, and S. Nakahara

Appl. Phys. Lett. 51, 975 (1987); http://dx.doi.org/10.1063/1.98781 (3 pages) | Cited 40 times

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We report measurements of the rate of growth of Ga and Sn clusters on clean Si surfaces. The volume rate of growth is linearly dependent on time, consistent with an Ostwald ripening mechanism for island growth. Activation energies for clustering, extracted from the temperature dependence, are shown to be sensitive to the underlying surface structure. This thermodynamical approach to the description of cluster formation is generally useful in determining the operational parameters and ultimate limits to heterostructure growth.
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68.35.B- Structure of clean surfaces (and surface reconstruction)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.35.Fx Diffusion; interface formation

Chemical structure of nitrogen in amorphous silicon matrix

Jagriti Singh and R. C. Budhani

Appl. Phys. Lett. 51, 978 (1987); http://dx.doi.org/10.1063/1.98782 (3 pages)

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Direct evidence of substitutional doping of nitrogen in ion beam deposited hydrogenated amorphous silicon, from analysis of infrared spectra and Si‐2p core level shape measured with x‐ray photoelectron spectroscopy (XPS), is presented. For the first time the XPS technique has been used to deduce the upper limit for substitutional solid solubility of the impurity.
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61.72.uf Ge and Si
66.30.J- Diffusion of impurities

Low‐temperature nitridation of fluorinated silicon dioxide films in ammonia gas

S. Aritome, M. Morita, T. Tanaka, and M. Hirose

Appl. Phys. Lett. 51, 981 (1987); http://dx.doi.org/10.1063/1.98783 (3 pages) | Cited 1 time

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A new technique of growing nitrided oxide at low temperatures has been developed. Fluorine‐enhanced thermal oxidation of silicon in O2+NF3 at temperatures below 800 °C and subsequent annealing of the fluorinated oxide in pure ammonia gas at the same temperature result in the formation of nitrided oxide. The dielectric breakdown strength of the fluorinated oxide is improved by the nitridation. Also, the nitrided oxide acts as a protective layer against alkaline ion contamination.
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81.05.Kf Glasses (including metallic glasses)
81.65.-b Surface treatments
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
77.22.Jp Dielectric breakdown and space-charge effects
77.55.-g Dielectric thin films

Room‐temperature operation of hot‐electron transistors

A. F. J. Levi and T. H. Chiu

Appl. Phys. Lett. 51, 984 (1987); http://dx.doi.org/10.1063/1.98784 (3 pages) | Cited 33 times

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We demonstrate the first room‐temperature operation of a double heterojunction unipolar hot‐electron transistor. Our test structure has a current gain greater than 10 and a measured current drive capability in excess of 1200 A cm−2. The device uses an indirect, wide‐band‐gap AlSb0.92As0.08 emitter and the transistor base is a 100‐Å‐wide InAs layer.
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85.30.De Semiconductor-device characterization, design, and modeling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Fq High-field and nonlinear effects
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Remote gate capacitance‐voltage studies for noninvasive surface characterization

R. R. Chang, D. L. Lile, and R. Gann

Appl. Phys. Lett. 51, 987 (1987); http://dx.doi.org/10.1063/1.98983 (3 pages) | Cited 1 time

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A measurement technique has been developed which allows noncontact capacitance‐voltage measurements to be made using a gate electrode located remote from the semiconductor surface under study. With gate electrodes ∼0.5 mm in diameter and gate to semiconductor separations ∼1500 Å we have been able to generate data entirely comparable to that obtained with integrated metal‐insulator‐semiconductor structures but with the advantage that we have access directly to the free‐semiconductor surface. We have applied this technique to bulk single‐crystal Si and InP samples and have been able to determine the effects of varying chemical treatments on the surface trap densities of the free surface. H2O2, for example, has been shown to create a poor InP surface whereas NRL etchant has yielded a surface seemingly quite close to the ideal.
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73.20.At Surface states, band structure, electron density of states
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.25.+i Surface conductivity and carrier phenomena
81.40.Rs Electrical and magnetic properties related to treatment conditions

Measurement of Au/GaAs/AlxGa1−xAs hetero‐Schottky barrier height and GaAs/AlxGa1−xAs conduction‐band discontinuity

H. Z. Chen, H. Wang, A. Ghaffari, H. Morkoç, and A. Yariv

Appl. Phys. Lett. 51, 990 (1987); http://dx.doi.org/10.1063/1.98785 (2 pages) | Cited 1 time

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A new hetero‐Schottky structure for the study of Schottky barriers and heterojunctions is discussed. Photoelectric measurements have revealed a correlation between Au/GaAs and Au/AlxGa1−xAs Schottky barrier heights and GaAs/AlxGa1−xAs heterojunction band offsets. The conduction‐band discontinuity ΔEc in the GaAs/AlxGa1−xAs system is determined, and the ratio ΔEc:ΔEg is found to vary between 69±5% and 58±5% for x=0.15–0.48.
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73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.-r Electrical properties of specific thin films
73.50.Pz Photoconduction and photovoltaic effects

Highly activated shallow Ga profiles in silicon obtained by implantation and rapid thermal annealing

H. B. Harrison, S. S. Iyer, G. A. Sai‐Halasz, and S. A. Cohen

Appl. Phys. Lett. 51, 992 (1987); http://dx.doi.org/10.1063/1.98786 (3 pages) | Cited 15 times

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The physical and electrical characteristics of gallium (Ga) ion implanted 〈100〉 silicon, annealed for times of the order of seconds to several tens of seconds for temperatures in the range of 550–900 °C, are presented. It is shown that for the chosen doses of 1–6×1015/cm2 and energy of 100 keV highly electrically active p‐type layers (approaching 100%) can be achieved. The highest activation being reached at temperatures below ∼650 °C with no profile distortion. For temperatures in excess of 800 °C this electrical activation decreases and significant profile movement occurs even for times as short as 2 s.
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81.40.Rs Electrical and magnetic properties related to treatment conditions
61.72.uf Ge and Si
66.30.J- Diffusion of impurities
72.80.Cw Elemental semiconductors

Theory of the steady‐state hole drift velocity in InGaAs

Kevin Brennan

Appl. Phys. Lett. 51, 995 (1987); http://dx.doi.org/10.1063/1.98787 (3 pages) | Cited 8 times

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We present calculations of the steady‐state hole drift velocity in Ga0.47In0.53As as a function of applied electric field based on an ensemble Monte Carlo method. The calculation uses no adjustable parameters in the determination of the scattering rates and contains the full details of the valence‐band structure derived using the k∗p method. It is found that the calculated values match recent experimental values within 20% in the saturated regime. The calculations are made over the applied field range of 10–250 kV/cm.
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72.20.Ht High-field and nonlinear effects
72.20.Dp General theory, scattering mechanisms
72.80.Ey III-V and II-VI semiconductors

Electric field and infrared‐induced recovery of metastability in amorphous hydrogenated silicon

E. Bhattacharya, J. I. Pankove, and S. K. Deb

Appl. Phys. Lett. 51, 998 (1987); http://dx.doi.org/10.1063/1.98788 (3 pages) | Cited 1 time

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In this letter we investigate the difference between the bond breaking and the charge trapping model of the light‐induced effect in amorphous hydrogenated silicon (a‐Si:H). We also report the partial recovery from the light‐induced effect in p‐i‐n solar cells by infrared illumination in the presence of an electric field.
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73.50.Pz Photoconduction and photovoltaic effects
84.60.Jt Photoelectric conversion
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors

Anomalous oxidation rate of silicon implanted with very high doses of arsenic

Seong S. Choi, M. Z. Numan, W. K. Chu, and E. A. Irene

Appl. Phys. Lett. 51, 1001 (1987); http://dx.doi.org/10.1063/1.98812 (3 pages) | Cited 5 times

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An anomalous increase in oxidation rate was observed during low‐temperature thermal oxidation of very high dose (5×1016, 7×1016/cm2) As+ ion implanted silicon. Oxidation of Si at 850 °C was faster than that at 950 °C. This effect was attributed to the snowplowing of arsenic (which was more pronounced at lower temperatures) creating a glassy Si‐O‐As layer near the Si‐SiO2 interface.
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81.65.-b Surface treatments
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
68.35.Fx Diffusion; interface formation
66.30.J- Diffusion of impurities

Critical layer thickness in In0.2Ga0.8As/GaAs single strained quantum well structures

I. J. Fritz, P. L. Gourley, and L. R. Dawson

Appl. Phys. Lett. 51, 1004 (1987); http://dx.doi.org/10.1063/1.98984 (3 pages) | Cited 91 times

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We report accurate determination of the critical layer thickness (CLT) for single strained‐layer epitaxy in the InGaAs/GaAs system. Our samples were molecular beam epitaxially grown, selectively doped, single quantum well structures comprising a strained In0.2Ga0.8As layer imbedded in GaAs. We determined the CLT by two sensitive techniques: Hall‐effect measurements at 77 K and photoluminescence microscopy. Both techniques indicate a CLT of about 20 nm. This value is close to that determined previously (∼15 nm) for comparable strained‐layer superlattices, but considerably less than the value of ∼45 nm suggested by recent x‐ray rocking‐curve measurements. We show by a simple calculation that photoluminescence microscopy is more than two orders of magnitude more sensitive to dislocations than x‐ray diffraction. Our results re‐emphasize the necessity of using high‐sensitivity techniques for accurate determination of critical layer thicknesses.
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68.55.-a Thin film structure and morphology
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.55.Cr III-V semiconductors

Nature of the E′ deep hole trap in metal‐oxide‐semiconductor oxides

H. S. Witham and P. M. Lenahan

Appl. Phys. Lett. 51, 1007 (1987); http://dx.doi.org/10.1063/1.98813 (3 pages) | Cited 45 times

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We have found through a sequence of ultraviolet illuminations, electron spin resonance measurements, and capacitance versus voltage measurements, that the E′ deep hole trap in metal‐oxide‐semiconductor silicon dioxide is a fundamentally reversible defect. Our results are totally consistent with an oxygen vacancy model for the E′ deep hole trap, but our results are inconsistent with the bond strain gradient model for the deep hole trap in metal‐oxide‐semiconductor silicon dioxide.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.61.Ng Insulators
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths

Er‐doped InP and GaAs grown by metalorganic chemical vapor deposition

Kunihiko Uwai, Hiroshi Nakagome, and Kenichiro Takahei

Appl. Phys. Lett. 51, 1010 (1987); http://dx.doi.org/10.1063/1.98814 (3 pages) | Cited 33 times

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Erbium is doped into InP and GaAs epitaxial layers for the first time by metalorganic chemical vapor deposition using tris‐cyclopentadienyl erbium [Er(C5H5)3]. Uniform doping as high as 1.5×1019 cm−3 across the entire depth of the epitaxial layers is revealed by secondary ion mass spectroscopy. Erbium‐related photoluminescence spectra around 1.54 μm from InP:Er and GaAs:Er show remarkable resemblance. At 2 K, in addition to the dominant zero phonon line at 1542 nm for InP:Er and at 1543 nm for GaAs:Er, several other zero phonon lines are observed at longer wavelengths. The Er‐related peak is observed at 1539±1 nm even at 300 K for InP:Er, shifting toward the shorter wavelengths by a little as 3 nm with increasing temperature from 2 to 300 K.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
78.55.Cr III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Electrical activity of defects in molecular beam epitaxially grown GaAs on Si and its reduction by rapid thermal annealing

N. Chand, R. Fischer, A. M. Sergent, D. V. Lang, S. J. Pearton, and A. Y. Cho

Appl. Phys. Lett. 51, 1013 (1987); http://dx.doi.org/10.1063/1.98815 (3 pages) | Cited 28 times

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The electrical activity of defects in GaAs grown on Si by molecular beam epitaxy (MBE) has been examined by studying the diode characteristics and deep level transient spectroscopy (DLTS) of Schottky barriers. The defects are not apparent from the forward bias diode characteristics but they are indicated by large leakage current and early breakdown under reverse‐biased conditions. Post‐growth rapid thermal annealing (RTA) has been found to significantly improve the diode behavior making it almost comparable to GaAs‐on‐GaAs. The reverse current in the as‐grown material shows a very weak temperature dependence, indicating that its origin is not thermionic emission or carrier generation. It is speculated that a large part of this current is due to defect‐assisted tunneling, which is reduced by RTA. DLTS indicated only a modest increase in the concentrations of the well‐known electron traps typical of MBE GaAs with no evidence for new levels in the upper half of the band gap.
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73.61.Ey III-V semiconductors
73.30.+y Surface double layers, Schottky barriers, and work functions
81.40.Rs Electrical and magnetic properties related to treatment conditions
85.30.Hi Surface barrier, boundary, and point contact devices

Low‐temperature electron transport in a one‐side modulation‐doped Al0.33Ga0.67As/GaAs/Al0.33Ga0.67As single quantum well structure

N. M. Cho, S. B. Ogale, and A. Madhukar

Appl. Phys. Lett. 51, 1016 (1987); http://dx.doi.org/10.1063/1.98816 (3 pages) | Cited 5 times

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The contributions of the remote ionized impurity scattering, alloy disorder scattering, and scattering due to band‐edge discontinuity fluctuation to the low‐temperature electron mobility in one‐side modulation‐doped Al0.33 Ga0.67 As/GaAs/Al0.33Ga0.67As single square quantum well structures are theoretically investigated via the memory function approach. The carrier wave functions and potential distributions used are obtained self‐consistently. Dependence of mobility on quantum well width and spacer layer thickness shows that mobilities of the order of 106 cm2 /V s can be achieved in such structures.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors
73.50.Bk General theory, scattering mechanisms
73.50.Dn Low-field transport and mobility; piezoresistance

Resonant tunneling through single layer heterostructures

H. C. Liu

Appl. Phys. Lett. 51, 1019 (1987); http://dx.doi.org/10.1063/1.98817 (3 pages) | Cited 74 times

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A new resonant tunneling process is discussed theoretically. The process relies on elastic intervalley transfers between different band minima, e.g., between Γ and X minima in a GaAs‐AlAs system. Single layer GaAs‐AlAs‐GaAs heterostructures are analyzed. An effective mass envelope function approach is used, and a delta‐function transfer potential at heterointerfaces is employed. A resonance in the transmission coefficient is clearly seen, which gives rise to a negative differential resistance region in the current‐voltage characteristic.
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73.40.Gk Tunneling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.61.Ey III-V semiconductors
85.30.De Semiconductor-device characterization, design, and modeling

SiO2/Si interface probed with a variable‐energy positron beam

Bent Nielsen, K. G. Lynn, Yen‐C Chen, and D. O. Welch

Appl. Phys. Lett. 51, 1022 (1987); http://dx.doi.org/10.1063/1.98818 (2 pages) | Cited 52 times

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The annihilation characteristics of a monoenergetic beam of positrons, after implantation in Si with a 350‐nm overlayer of SiO2, were measured as a function of mean implantation depth. Positrons implanted overlapping the SiO2/Si interface were observed to decay from a state with properties distinctively different from the state in bulk Si and the thermally grown SiO2, i.e., a positron interface state. The momentum distribution of the annihilating positron‐electron pair, as observed in the Doppler broadening of the annihilation line, is much broader for this state than for either bulk Si or SiO2, in contrast to previously observed localized positron states in solids and at surfaces which show a narrower distribution.
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78.70.Bj Positron annihilation
71.60.+z Positron states
68.35.B- Structure of clean surfaces (and surface reconstruction)

Elucidation of the organometallic vapor phase epitaxial growth mechanism for InP

N. I. Buchan, C. A. Larsen, and G. B. Stringfellow

Appl. Phys. Lett. 51, 1024 (1987); http://dx.doi.org/10.1063/1.99005 (3 pages) | Cited 24 times

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Organometallic vapor phase epitaxy has achieved remarkable recent success, becoming the most promising technique for the ultimate production of III/V materials and device structures. Unfortunately, our understanding of the growth process remains primitive. In this letter we report a new technique for tracing the reactions by conducting the epitaxial growth in a D2 ambient using a time‐of‐flight mass spectrometer to analyze the product molecules. The pyrolysis reactions were studied for PH3, both alone and in the presence of trimethylindium (TMIn), and for TMIn alone and in the presence of PH3. For the reactants alone, the PH3 pyrolysis is completely heterogeneous at the InP surface, while TMIn pyrolyzes mostly homogeneously in the gas phase. For TMIn and PH3 together, the reaction mechanism is entirely different, and the pyrolysis temperatures for both PH3 and TMIn are lowered. Since the reaction produces only CH4 molecules, with a complete absence of CH3D at high ratios of PH3 to TMIn, we hypothesize that InP growth is initiated by the direct interaction of TMIn and PH3 in the vapor phase.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)
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