摘要:

The effects of adding C2H4on the chemical vapor deposition (CVD) of SiO2films from SiH4/O2were studied at temperatures ranging from 673 to 1073 K using a hot‐wall‐type tubular reactor. Adding C2H4improved the step coverage of the films while effectively suppressing the gas‐phase formation of particles. Because C2H4is a well‐known radical scavenger, the control of gas‐phase chain reactions by consuming atom and/or radical species is responsible for the suppression of particle formation. Comparison of the sticking probability of growth species in SiH4/O2systems with and without added C2H4shows that high deposition temperatures are responsible for the improvement in step coverage. The analysis of the carbon content in the films by x‐ray photoelectron spectroscopy (XPS) shows no difference in carbon impurity levels between the SiH4/O2/C2H4and SiH4/O2chemical systems. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.113453

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Effect of a nitrogen electron‐cyclotron‐resonance (ECR) microwave plasma on near‐surface composition, crystal structure, and morphology of the As‐stabilized GaAs (100) surface is investigated with the use of digitally image‐processedinsitureflection high energy electron diffraction. Nitridation is performed on molecular beam epitaxially (MBE) grown GaAs surfaces near 600 °C under typical conditions for ECR microwave plasma‐assisted MBE growth of GaN films on GaAs. Brief plasma exposures (≊3–5 s) are shown to result in a specular, coherently strained, relatively stable, GaN film approximately one monolayer in thickness, which can be commensurately overgrown with GaAs while longer exposures (up to 1 min) result in incommensurate zincblende epitaxial GaN island structures. Specular and nonspecular film formations are explained in terms of N‐for‐As surface and subsurface anion exchange reactions, respectively. Commensurate growth of ultrathin buried GaN layers in GaAs is achieved. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113454

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A &dgr;‐dopedGaAs/In0.2Ga0.8Asp‐channel heterostructure field‐effect transistor grown by low‐pressure metalorganic chemical vapor deposition is demonstrated. The mobilities and two‐dimensional hole gas concentrations at 300 (77) K are 260 (2600)cm2/v sand 1012(5.5×1011) cm−2, respectively. For a gate length of 1.5 &mgr;m, the maximum extrinsic transconductances are 15 mS/mm at 300 K and 24 mS/mm at 77 K. The high transconductances extend a wide range versus gate voltage. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113455

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A correlation between the partial pressure of dichlorosilane gas (SiH2Cl2) and the incorporation of oxygen (O) and chlorine (Cl) atoms into the low‐temperature (850 °C) epitaxial films was found. The profiles of O and Cl concentrations in the epitaxial films were measured by secondary ion mass spectroscopy. Incorporation of O and Cl atoms into the growth films during the epitaxial growth was suppressed by increasing the partial pressure of SiH2Cl2. The growth rate linearly increased with the partial pressure of SiH2Cl2and eventually saturated. Incorporation of O atoms was inhibited and fine removal of Cl atoms was achieved when the growth rates saturated. The epitaxial films with high O and Cl concentrations had a microroughened surface (root mean square of microroughness ≳0.4 nm). The microroughness was also improved by increasing the partial pressure of SiH2Cl2. The coverage of kinks and/or hollow bridge sites by hydrogen (H) and Cl atoms seems to restrict the reaction of O and water (H2O) with the growth front surface. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.113456

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The cleaning of the GaAs (111)B surface with a hydrogen electron cyclotron resonance discharge plasma is investigated at temperatures between 200 and 500 °C and compared with the GaAs (100) surface. It is found that during the exposure the GaAs (111)B is etched in a non‐Arrhenius way with a higher etch rate at low temperatures. For temperatures 300–500 °C, the surface is severely roughened after exposure, while the (100) surface remains smooth in all cases. The near‐surface crystalline quality of GaAs (111)B remains higher than that of (100).

ISSN:0003-6951    

DOI:10.1063/1.113457

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A study of the effect of growth parameters on the resulting crystalline quality of CdTe epilayers grown by metalorganic chemical vapor deposition (MOCVD) technique is reported. The crystalline quality of the MOCVD CdTe (111)B epilayers is investigated by the double crystal rocking curve (DCRC) and Laue x‐ray diffraction techniques. The rocking curve full width at half‐maximum (FWHM) is used as a quantitative measure of structural perfection of the epilayers. The results indicate that a major parameter that affects the crystalline quality is the growth temperature. Epilayers grown at 480 °C exhibit high crystalline quality that is hardly affected by the partial vapor pressure of the metalorganic sources or the growth rate, whereas these growth parameters strongly affect the crystalline quality of epilayers grown at 430 °C. This phenomenon is attributed to the different mechanisms governing the growth process at these growth temperatures, namely mass transfer and surface kinetics. The crystalline quality of the MOCVD CdTe layers grown on the (111)B face of CdZnTe (4% Zn) or CdTe substrates can consistently match that of MOCVD (001) layers previously considered to have the best crystalline quality, with FWHM less than 90 arcsec for 6–7 &mgr;m thick layers. Linewidths as narrow as 56 arcsec are observed for epilayers thicker than about 11 &mgr;m. Microtwins, identified by the sixfold symmetry of Laue and double crystal 360° &fgr;‐scan diffraction patterns, are present even in epilayers with the narrowest FWHM. No straightforward correlation between visual morphology and crystalline quality was found. The growth of CdTe or CdZnTe epilayers is proposed by the MOCVD technique as buffer layers to obtain super substrates (‘‘superstrates’’) for the subsequent liquid phase epitaxy (LPE) growth of HgCdTe layers and additional heterostructures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113458

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The avalanche breakdown voltage (Vb) has been measured in a range of bulk AlxGa1−xAs alloys and Al0.3Ga0.7As/GaAs multilayer structures. The bulk alloys show a linear dependence ofVbonxup to at leastx=0.6. Multilayers with thin (≤100 A˚) dimensions follow this trend, withVbbeing determined by the average Al fraction of the multilayer ‘‘pseudoalloy’’. For thicker (≥500 A˚) layersVbtends to a mean of the bulk values of the layers. The transition from pseudoalloy to bulklike behavior is interpreted in terms of the momentum and energy relaxation lengths, estimated for bulk GaAs using a Monte Carlo solution of the semiclassical transport equation. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113459

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Random telegraphic signals (RTS) are observed in the forward‐biased dc base current of electrically stressed silicon bipolar transistors. The RTS noise in the base current is shown to originate from random trapping of electrons at the stress‐created oxide and interface traps located over the oxide‐covered emitter‐base junction space‐charge region. The observed pulse width (∼0.1–100 s), the uniform height of the pulses (∼1% of dc base current), and their dependencies on temperature andVBE(emitter/base bias voltage), exp(qVBE/nkT) withn=2, are interpreted by the two‐step model consisting of electron tunneling between the oxide and interface traps, and the recombination of Si band electrons and holes at the interface traps. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113460

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Oxynitride films grown on preoxidized (100) silicon surfaces in a nitric oxide (NO) ambient at 950 °C have been investigated using x‐ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), atomic force microscopy (AFM), and cross‐sectional transmission electron microscopy (XTEM). Compared to N2O oxynitride, NO oxynitride exhibits very different surface chemistry, interface properties, and growth mechanisms. The etch back of NO and N2O oxynitride films allows control of sample thickness for the XPS measurements. NO oxynitride has the interfacial nitrogen (Nint) sharply peaked on the Si substrate side of the interface, while it is broad and on the dielectric side of the interface for the N2O oxynitride. The N(1s) XPS results reveal a clear distinction between N2O oxynitride and NO oxynitride. Near the Si/dielectric interface the NO oxynitride shows primarily Si≡N bonds, while the N2O films showed a N(1s) binding energy peak that is in‐between that of Si≡N bonds and Si2=N—O bonds. Furthermore, the NO oxynitride surface roughness as determined by AFM is lower than that of the Si/SiO2interface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113461

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The inherent optical anisotropy of a strained [110]‐oriented multiple quantum well structure is used to make an optically addressed light modulator based on polarization rotation. The anisotropy of the multiple quantum well absorption coefficient for orthogonal polarizations causes rotation of the plane of polarization of light passing through the structure. By partially bleaching the quantum well exciton, the amount of polarization rotation is changed, and therefore modulation of the amplitude of the transmitted beam is achieved. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113462

出版商:AIP    

年代:1995

数据来源: AIP