摘要:

We present results on the thermal stability as well as the thermally induced hydrogen, hydrocarbon, and nitrogen–hydrogen effusion from thin films of Group III nitrides prepared by low‐pressure chemical vapor deposition from organometallic precursors. We have deposited amorphous, polycrystalline, and epitaxial InN, GaN, and AIN films on (0001) Al2O3substrates using the chemical reaction of azido[bis(3‐dimethylamino)propyl]indium, triethylgallium, and tritertiarybutylaluminium with ammonia. The substrate temperature was varied between 400 °C and 1100 °C. The elemental composition, in particular its dependence on the growth temperature, was investigated by elastic recoil detection analysis (ERDA). The influence of growth rate and crystallite size on the concentration of surface adsorbed hydrocarbons and carbon oxides is determined by a combination of ERDA and thermal desorption measurements. In addition, the stability of and the nitrogen flux from the InN, GaN, and AIN surfaces was determined by x‐ray diffraction and thermal decomposition experiments.

ISSN:0734-211X    

DOI:10.1116/1.588793

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

This article describes thermally stable Schottky contacts using low N content double layered WSiN for InGaP/(In)GaAs metal–semiconductor field‐effect transistors with self‐aligned ion‐implantedn+layers. Transmission electron microscopy observations show that the microscopic interfacial reaction between WSiN and GaAs is completely suppressed when N content in the WSiN is 10% or less. As a result, a WSiN/GaAs‐cap/InGaP Schottky contact shows high thermal stability after annealing at 800 °C for 100 min, even though the GaAs cap is as thin as 25 Å. Moreover, the double‐layer WSiN structure suppresses reduction in the carrier concentration in the channel during activation annealing. The carrier concentration of the GaAs‐cap (40 Å)/InGaP (100 Å)/ InGaAs‐channel (100 Å) film, 6.5×1018cm−3, decreases to less then 2×1018cm−3with low N content WSiN (N=10%, 4000 Å) after annealing at 900 °C for 0.1 s, but it remains 3.8×1018cm−3with the double layered WSiN (N=37%, 3800 Å/N=10%, 200 Å).

ISSN:0734-211X    

DOI:10.1116/1.588794

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

GaAs/Al0.3Ga0.7As tilted T‐shaped quantum wires (T‐QWRs) were fabricated by growing Al0.3Ga0.7As/GaAs (well thickness of GaAsLw=4.4 nm) on a (111)Bfacet plane that was formed when a GaAs/Al0.3Ga0.7As multi‐quantum well (MQW) layer (Lw=4.5 nm) was grown on a reverse‐mesa etched GaAs(100) substrate by glancing‐angle molecular beam epitaxy (GA‐MBE). Growth conditions of the tilted T‐QWR were optimized, and full width at half‐maximum (FWHM) of a cathodoluminescence (CL) peak from the tilted T‐QWRs was reduced down to 19 meV at 78 K, which is about one‐third of that (61 meV) of previous GaAs/Al0.3Ga0.7As tilted T‐QWRs.

ISSN:0734-211X    

DOI:10.1116/1.588795

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Standard molecular beam epitaxy is used to demonstrate the growth feasibility and reproducibility on the formation of microfacet array on the top surface of higher‐index (311)A quantum well structures. The quasiperiodic microfacet array was characterized by atomic force microscopy and was observed to be along the [2̄33] direction, whereas for the (100) reference sample the microscopic surface morphology presented the terraces formation. We have used photoluminescence to characterize the optical properties of the samples. The observed redshift of the luminescence from the (311)A sample, in relation to the (100) reference sample, was correlated with the existence of a lateral confinement potential induced by the period of faceting in this structure. The comparative analysis based on photoluminescence measurements have also shown the higher quality and the lower impurity incorporation for the (311)A oriented samples.

ISSN:0734-211X    

DOI:10.1116/1.588796

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Scanning tunneling microscopy results show that heating a nearly saturated Br–GaAs(110) 2×1/c(2×2) surface to 600 K leads to a random distribution of single‐layer deep vacancy islands. These islands expand via continued etching upon heating to 700 K. Subsequent exposure to Br2at 625 K results in complete removal of the first layer via step retreat. Accordingly, monolayer etching can be achieved. The different etching pathways of the exposure‐annealing treatment and that of continuous etching are discussed.

ISSN:0734-211X    

DOI:10.1116/1.588797

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The surface composition, etch rates, and surface roughness of indium phosphide (InP) surfaces treated in radio frequency (rf) hydrogen and hydrogen/argon/methane plasmas have been investigated usinginsituAuger spectroscopy andexsituscanning electron microscopy and atomic force microscopy. In agreement with most previous studies, hydrogen plasmas are found to completely remove surface carbon and oxygen impurities, but at the expense of some degree of surface phosphorus depletion. This depletion can be minimized by utilizing brief plasma exposure times and low rf power settings. Oxygen removal is found to be rate limiting in the production of a clean surface. InP etching in hydrogen/argon/methane can be performed either in a low density, capacitively coupled plasma mode, or in a high density, inductively coupled plasma mode. For operation in the low density regime, the etched surfaces have a constant and nearly stoichiometric composition, independent of plasma parameters. Etch rates vary from ∼20–400 Å/min, while the root mean square (rms) surface roughness varies from ∼20 to>400 Å. Both of these quantities show definite trends with changing plasma parameters, and, in particular, high etch rates and low surface roughness are both favored by increasing total plasma pressure and methane flow rate. Within the ranges studied, the etch rate is most strongly affected by the amount of hydrocarbon species reaching the surface, which can remove indium in the form of indium alkyl products. However, sputtering effects are also shown to be significant. Etching InP in the high density plasma mode gives an etch rate of ∼700 Å/min, but only at the expense of severe surface phosphorus depletion and rms surface roughness of ∼2000 Å. The breakdown of methane within the plasma under these conditions may serve to inhibit indium alkyl formation, and hence lead to the observed phosphorus depletion.

ISSN:0734-211X    

DOI:10.1116/1.588798

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The behavior of monolayer‐deep holes on the surface of (001) GaAs grown by molecular beam epitaxy during post‐growth annealing is observed byinsituscanning electron microscopy. Most small holes disappear immediately after growth in the same way as the islands. However, it is found that some are left for a long time and form big holes with each other. These residual big holes are elongated in the [110] direction initially. They extend in the [110]direction and coalesce with each other, but, at the same time, they shrink in the [1–10] direction and become elongated in the [110]direction. Finally they shrink in both directions and disappear. It takes about 10 min for all the holes to disappear, which is much longer than the growth interruption period usually employed to smooth heterointerfaces. The anisotropic behavior of big holes are discussed in relation to the reported growth anisotropy.

ISSN:0734-211X    

DOI:10.1116/1.588545

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Schottky barrier structures formed on epitaxial GaAs:Sb have been studied at different Sb concentrations (0–1×1020cm−3) and different temperatures (80–300 K). Current–voltage (I–V) characteristics have been numerically simulated and compared with the experimental measurements in an attempt to reveal the dominant current transport mechanism. Since Sb is a nonelectrically active dopant in GaAs but efficiently influences defect ensemble, the role of the defects on the electrical characteristics of the device structures could be investigated. Three different regions of Sb doping have been considered in accordance with a previous study of the structural and electronic properties of metal organic vapor phase epitaxy‐grown GaAs:Sb. The current transport in the samples containing an optimum amount of Sb (respectively, minimum defects) is dominated by a thermionic field emission in the main operation bias range, although indications of Poole–Frenkel effect are observed, related to the intrinsic near mid‐gap electron levels. In the undoped and highly doped samples the current is mainly due to a carrier diffusion mechanism. In addition, the large amount of defects in these samples results in an electron tunneling component which is present in theI–Vcharacteristics.

ISSN:0734-211X    

DOI:10.1116/1.588546

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

〈110〉 60° and 〈100〉 edge misfit dislocations in In0.06Ga0.94As heterostructures grown on patterned GaAs (001) substrates with relatively low misfitf(f=0.0043) have been investigated. The reduction of 〈110〉 misfit dislocation density on mesas is observed by cathodoluminescence, while the 〈100〉 misfit dislocation density on mesas observed by synchrotron radiation double crystal topography remains unchanged. The critical thickness is calculated by modifying the Matthews mechanical equilibrium theory introduced by Chidambarraoetal. The calculated results can be applied to both the nonpatterned area and the sidewalls of the mesa. The critical thickness of one side of the mesa is larger than that of nonpatterned areas. The critical thickness of both sides of mesas is dependent on the angle between the sidewall and (001) GaAs. This is likely due to different values of cos φ/sin ψ, which determines the values of the friction forceFFwith different sidewall angles. It is suggested that the 〈100〉 misfit dislocations are generated by climb and they can cross mesas by climbing along 〈100〉 directions.

ISSN:0734-211X    

DOI:10.1116/1.588730

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We report on secondary ion mass spectrometry (SIMS) depth profile artifacts induced by surface roughness. The formation of a TiSi2film at 800 °C on a boron doping superlattice (DSL) of Si results in a rough (22.0 nm root mean square) interface between the film and Si DSL. After chemically etching off the TiSi2film, SIMS information is collected while sputtering through the surface of the Si DSL. The resulting depth profiles are irreproducible due to the initial surface roughness. By chemo‐mechanically polishing the Si prior to SIMS analysis, we smooth the surface and the resulting depth profiles are then consistent and easily explained by current diffusion theory.

ISSN:0734-211X    

DOI:10.1116/1.588731

出版商:American Vacuum Society    

年代:1996

数据来源: AIP