摘要:

The growth of high‐purity GaAs by chemical beam epitaxy using triethylgallium and arsine is reported. Purity of the epilayer is affected by the cracking efficiency of arsine, V/III ratio, and the substrate temperature. Samples generally showp‐type conductivity with carbon as the residual impurity. The growth conditions to achieve net carrier concentration below 1014cm−3are identified. The low‐temperature photoluminescence spectrum shows well‐resolved excitonic structures, an indication of excellent optical quality.

ISSN:0003-6951    

DOI:10.1063/1.98755

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Etching of Y‐Ba‐Cu‐O superconducting thin films has been accomplished using a pulsed excimer laser (248 nm, 30 ns). Etch depth as a function of the number of laser pulses was linear over a wide range of incident laser energy densities. An etch threshold energy density of 0.11 J/cm2was observed and etch rate per pulse scaled linearly with the logarithm of the incident energy density. The dependence is adequately explained by a linear absorption model with an inverse absorption length of 2.3×105cm−1.

ISSN:0003-6951    

DOI:10.1063/1.98756

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The resistivity of Ba2YCu3Oxwas measured in the 450–850 °C range at various oxygen partial pressures. The tetragonal to orthorhombic phase transition is observed as a change in the slope of the resistivity curve. The lack of a discontinuity in the curve is consistent with the phase transition being higher than first order. It was found that decreasing the oxygen contentxbelow 6.2 changed the resistivity of the tetragonal phase from metallic character to semiconducting character. In the metallic region of the tetragonal phase the superconducting transition temperature is depressed below 60 K, while in the semiconducting region, no superconducting onset was observed down to 6 K. In the orthorhombic phase, the resistivity of the material is shown to be governed by the number of oxygens per unit cell, suggesting that the resistivity can serve as a quality control parameter in the production of superconducting devices.

ISSN:0003-6951    

DOI:10.1063/1.98757

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

High‐resolution x‐ray photoemission and inverse photoemission have been used to study the microscopic formation of Au overlayers on the highTcsuperconductor La1.85Sr0.15CuO4. Our results indicate that Au does not induce disruption or surface reaction, unlike the reactive transition metals. The electronic states of the superconductor are attenuated as the Au overlayer covers the surface. We conclude that Au is a promising material for metallization and for passivation.

ISSN:0003-6951    

DOI:10.1063/1.98758

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

n‐Si/non‐liquid electrolyte interfaces have been realized in order to obtain electron accumulation layers of very high concentration at various temperatures. The interface has been characterized by using standard electrochemical measurements and the two‐dimensional electron gas has been studied by transconductance and infrared optical absorption measurements. These interfaces are found to exhibit densities as high as 4×1013electrons cm−2. These results are compared with available data on analogousn‐Si/organic‐solvent electrolyte interfaces.

ISSN:0003-6951    

DOI:10.1063/1.98759

出版商:AIP    

年代:1987

数据来源: AIP