摘要:

Effects of extended defect evolution on the anomalous diffusion of ion‐implanted boron during rapid thermal annealing (RTA) have been studied using transmission electron microscopy and secondary‐ion mass spectroscopy. It has been found that for low‐dose boron implants (<1×1014cm−2), no extended defects can be observed after RTA at 1000 °C, and the anomalous diffusion saturates within less than 10 s. However, extended defects are developed for high‐dose boron implants (>5×1014cm−2), and the anomalous diffusion persists for a much longer time and is dose dependent. Extended defect evolution has been characterized and correlated with the observed anomalous boron diffusion behaviors.

ISSN:0003-6951    

DOI:10.1063/1.102529

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

AlxGa1−xN‐GaN quantum wells were grown on basal plane sapphire by low‐pressure metalorganic vapor deposition. The photoluminescence spectra of samples of different well thicknesses andxvalues were measured. The experimental data were compared with the calculated solutions of the finite square quantum well and the bound states involved in the optical transition were identified.

ISSN:0003-6951    

DOI:10.1063/1.102530

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Using high dose implantation of Cr+into (111)‐oriented Si, followed by annealing, we have created continuous, buried layers of CrSi2in Si. The layers are stoichiometric and epitaxially aligned along one of the substrate ⟨111⟩ directions. Results of temperature‐dependent resistivity and Hall measurements on the early layers show that they arep‐type degenerate semiconductors consistent with data for bulk samples. More recent layers appear to be single crystal with [0001] parallel to [111] and arentype with lower carrier density.

ISSN:0003-6951    

DOI:10.1063/1.103334

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It is shown for the first time that carbon behaves predominantly as an acceptor in InGaAs and AlInAs under co‐implantation conditions. The co‐implanted ion, regardless of species, acts to create vacant lattice sites for occupation by the carbon. Implantation of 40 keV carbon ions alone at doses between 5×1012and 5×1014cm−2followed by annealing in the range 600–950 °C for 10 s does not produce any measurable electrical activity in either material. In InGaAs, carbon implantation at 5×1014cm−2produced net acceptor activations of 20, 11, or 6% for Ga, Ar, or As co‐implantation, respectively, at the same doses after 700 °C, 10 s anneals. Similar results were obtained for AlInAs after annealing at 900 °C. The diffusion coefficient for carbon is estimated from secondary‐ion mass spectrometry measurements to be less than 3.3×10−14cm2  s−1at 800 °C in both materials.

ISSN:0003-6951    

DOI:10.1063/1.102531

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have used deep level photoluminescence spectroscopy to investigate the surface electronic quality of molecular beam epitaxy (MBE) grown CdTe layers during ultrahigh vacuum cleaning. Spectra are highly sensitive to heat treatment, contamination, and electron beam exposure. The technique provides a guide to growth and cleaning of MBE films of optimal electronic quality, which exhibit intense near‐band‐edge and minimal deep level emission and which exceed substantially the electronic quality of bulk CdTe crystals.

ISSN:0003-6951    

DOI:10.1063/1.102532

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Photoreflectance‐derived band‐gap parameters as a function of temperature for InGaAs and InAlAs lattice matched to InP are reported. The experiment was performed on a set of samples of various compositions (and strains) yielding greater reliability and ensuring self‐consistency. For InGaAs, fits to the Varshni equation gaveE0(T=0 K)=803 meV, &agr;=4.0×10−4eV K−1, and &bgr;=226 K. For InAlAs,E0(T=0 K)=1.541 eV, &agr;=4.7×10−4eV K−1, &bgr;=149 K, and &Dgr;0=338 meV.

ISSN:0003-6951    

DOI:10.1063/1.102533

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Epitaxial ZnSe/epitaxial GaAs interfaces have been formed by molecular beam expitaxy and evaluated by several techniques including capacitance‐voltage measurements. In the study reported here, the GaAs surface stoichiometry was systematically varied prior to the nucleation of ZnSe. A dramatic reduction of interface state density occurred when the GaAs epilayer was made As deficient. The resulting interface state densities of as‐grown structures are comparable to values obtained with (Al,Ga)As/GaAs interfaces.

ISSN:0003-6951    

DOI:10.1063/1.102534

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Experiments involving the epitaxial growth of GexSi1−xfilms by chemical vapor deposition have shown that the addition of germane greatly enhances the growth rate, compared to that seen with dichlorosilane alone. Careful analysis shows that the increase is not accounted for by summing the individual growth rates, but clearly indicates that the silicon growth rate is catalyzed. The magnitude of the effect increases at lower temperatures, with a two orders of magnitude increase seen at 625 °C.

ISSN:0003-6951    

DOI:10.1063/1.102535

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have studied the photoreflectance spectra at 300 K from a number of GaAs/Ga1−xAlxAs heterojunction bipolar transistor (HBT) structures grown by molecular beam epitaxy and metalorganic chemical vapor deposition. From the observed Franz–Keldysh oscillations we have been able to evaluate the built‐in dc electric fieldsFdcin the Ga1−xAlxAs emitter as well as then−‐GaAs collector region. In addition, the Ga1−xAlxAs band gap (and hence Al composition) has been determined. The obtained values ofFdcare in good agreement with numerically computed values for the analyzed HBT structures, thus making it possible to deduce doping levels in these sections.

ISSN:0003-6951    

DOI:10.1063/1.102536

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have synthesized new superconductors of nearly single phase with zero‐resistance temperatures around 120 K employing a novel method for sintering. The samples included a nominal composition of (Tl0.64Pb0.2Bi0.16)Sr2Ca3Cu4Oz. This sample was prepared from the mixture of presynthesized (Tl0.64Pb0.2Bi0.16)Sr2CaCu2Oz(1212 phase), CaO, and CuO powders. The mixed powder was sintered at 920 °C in O2gas and post‐annealed at 400–600 °C in O2gas. The powder x‐ray diffraction revealed that the sample was isostructural with the Tl‐based (Tl, Pb, Bi)Sr2Ca2Cu3Oz(1223 phase). The sample exhibited a sharp superconducting transition atTonsetc=125 K andTR=0c=120 K and the superconducting diamagnetic signal at 10 K was about 20% of a full Meissner effect.

ISSN:0003-6951    

DOI:10.1063/1.103174

出版商:AIP    

年代:1990

数据来源: AIP