摘要:

Low‐temperature selective silicon epitaxial growth using a dichlorosilane‐hydrogen mixture in a low‐pressure chemical vapor deposition hot‐wall reactor has been studied. A simple HF vapor treatment effectively removes surface oxides and passivates the Si surface prior to reactor loading. The addition of a small concentration of dichlorosilane to the H2ambient during the prebake at a temperature of 900 °C improves selective epitaxial quality both by maintaining an oxide‐free surface, and by suppressing undercut of oxide‐covered regions. With these process improvements defect‐free, selectively overgrown Si epitaxial layers are achieved at deposition temperatures between 800 and 850 °C.

ISSN:0003-6951    

DOI:10.1063/1.104444

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Ion‐induced damage accumulation has been measured as a function of ion dose and dose rate following 100 keV Si+room‐temperature implants in GaAs. The dose rate has been found to have a strong effect on the total damage produced in GaAs over a range of dose between 1014and 1015/cm2and implantation current densities from 0.05 to 12 &mgr;A/cm2. Two distinct stages of damage formation have been identified. At low implantation doses, damage accumulates slowly and tends to saturate at a level of approximately 0.4×1017defects/cm2. However, beyond a threshold dose (≊1014Si/cm2) which decreases with increasing dose rate, damage accumulates rapidly. In the second stage, the onset of which appears to be associated with the formation of more complex damage structures, the total damage and the damage accumulation rate were found to increase with dose rate for a fixed ion dose. For comparison, dose rate effects were also measured in Si and Ge under similar implant conditions and found to be weaker. The results for GaAs are correlated with recent observations of dose‐rate‐dependent electrical activation in Si‐implanted GaAs.

ISSN:0003-6951    

DOI:10.1063/1.104445

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The low‐temperature limit to GaAs molecular beam epitaxy (MBE) is studied at temperatures from 250 °C to room temperature. Using transmission electron microscopy of layers grown under a variety of conditions we show that, as for Si MBE, there is an epitaxial thicknesshepiat which a growing epitaxial layer becomes amorphous. The temperature, growth rate, composition, and defect density all appear to be constant during growth of the epitaxial layer, and (in analogy with Si MBE) we tentatively associate the breakdown of epitaxy athepiwith roughening of the growth surface. We demonstrate thathepidepends strongly on composition, increasing rapidly with Ga/As ratio at fixed temperature. At fixed Ga/As ratio,hepishows an abrupt increase from <200 to ≳5000 A˚ at 210 °C. The results have implications for the growth of GaAs/GaAs for high‐speed photodetectors, as well as possible applications to GaAs/Si heteroepitaxy.

ISSN:0003-6951    

DOI:10.1063/1.104446

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

In as‐grown GaP we investigated two phosphorous antisite related electron spin resonance spectra with respect to ligand hyperfine (lhf) interactions: basing upon a linewidth analysis, we attribute a hyperfine doublet with unresolved lhf structure (PA3) inn‐GaP:S to a P‐antisite defect with cubic symmetry. The lhf interaction of the well known lhf resolved PP4doublet (PA1) in semi‐insulating GaP:Cr was found to be temperature dependent. In plastically deformed GaP the two spectra showed contrary linewidth changes. In highly deformedn‐GaP:S both signals were detectable. A new spectrum of low symmetry (GA1) was observed which we attribute to a gallium antisite related defect.

ISSN:0003-6951    

DOI:10.1063/1.104447

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Inverted pseudomorphic high electron mobility transistor (HEMT) and inverted HEMT heterostructures are demonstrated by atmospheric pressure metalorganic chemical vapor deposition (MOCVD) for the first time and characterized by transmission electron microscopy (TEM), variable temperature Hall effect, and Shubnikov–de Haas measurements. TEM micrographs of both structures show distinct and sharp heterojunction interfaces without indications of interface roughness at the AlGaAs/channel layer interface. Variable temperature Hall effect measurements reveal a monotonic increase in mobility as the temperature is lowered. For the inverted HEMT, the mobility at 15 K is 90 000 cm2/V s with a sheet density of 8.2×1011cm−2. The mobility of the inverted pseudomorphic HEMT at 15 K is 73 000 cm2/V s with a sheet density of 1.5×1012cm−2. Shubnikov–de Haas measurements at 4.2 K in magnetic fields up to 18.5 T show clear magnetoresistance oscillations and plateaus in the quantum Hall effect confirming the existence of a two‐dimensional electron gas. Fast Fourier power transform of the magnetoresistance versus magnetic field shows two subband levels with a total sheet density of 8.7×1011cm−2for the inverted HEMT and a total sheet density of 1.55×1012cm−2for the inverted pseudomorphic HEMT in close agreement to the variable temperature Hall effect measurement results.

ISSN:0003-6951    

DOI:10.1063/1.104448

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Post‐growth patterning to <15 &mgr;m×15 &mgr;m size patterns combined with thermal annealing at 850 °C for ≳15 min eliminates the dark line defects (DLDs) in GaAs‐on‐Si as shown by the spatially resolved photoluminescence technique. Patterning to small size islands of GaAs facilitates dislocation migration laterally out of the crystal, and thermal annealing provides the activation energy for the dislocations to migrate and interact. Patterning to small size features also significantly reduces the thermally induced biaxial tensile stress as reported earlier. On large size patterns, the density of DLDs is significantly reduced near the surface leaving larger volume of the material free from DLDs.

ISSN:0003-6951    

DOI:10.1063/1.104449

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

High quality AlxGa1−xAs has been grown by low‐pressure (30 Torr) organometallic vapor phase epitaxy (OMVPE) using a novel precursor, trimethylamine alane (TMAAl), as the aluminum source. The epilayers exhibited featureless surface morphology, very strong room‐temperature photoluminescence (PL), and excellent compositional uniformity (x=0.235±0.002 over a 40 mm diameter). The residual carbon incorporation, which determined the background doping, depended largely upon the choice of gallium precursor. Using triethylgallium, carbon incorporation could be largely suppressed ([C]≪1016cm−3). The carbon‐related emission intensity was less than the bound exciton emission in low‐temperature (1.6 K) PL even at excitation powers as low as 50 &mgr;W cm−2. By sharp contrast, the use of trimethylgallium led to much higher C concentrations (2–5×1017cm−3). Under appropriate conditions, therefore, the use of TMAAl produces extremely high purity AlGaAs of superior quality to AlGaAs grown using conventional precursors.

ISSN:0003-6951    

DOI:10.1063/1.104450

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have demonstrated, for the first time, that the epitaxial growth temperature can be lowered by dopant incorporation using rapid thermal processing chemical vapor deposition. Heavily arsenic‐doped epitaxial layers with very abrupt dopant transition profiles and relatively uniform carrier distributions have been achieved at 800 °C. In addition, it is found that defect formation is closely related to dopant concentration.

ISSN:0003-6951    

DOI:10.1063/1.104452

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report the electrical characterization of GaAsPiNjunction diodes grown over the sidewalls of patterned trenches by atomic layer epitaxy. The diodes exhibit excellent rectifying behavior demonstrating that high quality GaAs was grown on the entire trench structure including sidewalls and corners. The sidewall material is characterized electrically through reverse bias diode leakage from thermal generation in the depletion region. 2‐&mgr;m‐deep trenches contribute a leakage current of less than 60 &mgr;A/cm2of sidewall area under 1 V reverse bias at 144 °C, which is satisfactory for most device applications.

ISSN:0003-6951    

DOI:10.1063/1.104453

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Using metal‐oxide‐semiconductor (MOS) structures, the shift of centroid (peak) of &ggr;‐ray energy distributions emitted from positron annihilation has been measured as a function of incident positron energy. The Doppler centroid shift was found to be consistent with the positron motion in the MOS depletion region. The results are described by a one‐dimensional positron diffusion model, and provide information on ‘‘effective’’ positron diffusion length under applied field.

ISSN:0003-6951    

DOI:10.1063/1.104399

出版商:AIP    

年代:1991

数据来源: AIP