摘要:

The formation of &bgr;‐SiC during rapid thermal chemical vapor deposition of an epitaxial Si layer on a (100) Si substrate has been demonstrated using high‐resolution cross‐sectional transmission electron microscopy and secondary ion mass spectrometry (SIMS) depth profiling. Ellipsoidal &bgr;‐SiC precipitates (3×10 nm2average size) were found with a density of (6±1)×109cm−2along the epilayer/substrate interface. SIMS revealed about 0.2 monolayer of carbon concentrated at the interface. The precipitates were shown to form during the hydrogen prebake as a result of improper surface cleaning. The crystalline quality of the epitaxial layer, however, was unaffected by the presence of the &bgr;‐SiC.

ISSN:0021-8979    

DOI:10.1063/1.345559

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Impurity‐induced layer disordering experiments on AlxGa1−xAs‐GaAs quantum well heterostructures (QWHs) that are doped heavily with carbon are described. The data show that carbon doping retards Al‐Ga interdiffusion relative to an undoped crystal, and that interdiffusion in C‐doped QWHs is not enhanced by a Ga‐rich (versus As‐rich) annealing ambient. The data are inconsistent with most Fermi‐level‐effect models for layer disordering that do not include chemical impurity dependence or sublattice dependence, and that do not consider the possibility of inhibited Al‐Ga interdiffusion in extrinsic crystals.

ISSN:0021-8979    

DOI:10.1063/1.345560

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The effects of dc transport current on low‐field microwave absorption have been investigated systematically on bulk ceramic YBa2Cu3O7−&dgr;samples. At a fixed temperatureT, the critical currentIc(T) at which the electron paramagnetic resonance (EPR) signal vanishes varies linearly withT. The EPR absorption characteristics obey a scaling rule in accordance with the flux creep model. A revised version of the flux creep model is also presented.

ISSN:0021-8979    

DOI:10.1063/1.345561

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Electrical responses of shock‐loadedX‐cut quartz crystals were studied using laser‐produced stress pulses. For acoustic transit times that are long compared to the duration of the stress pulse, two short‐circuit current signals were observed. The amplitude of the current signal from the rear electrode is predicted to be twice that obtained from the ground electrode using a one‐dimensional analysis of the dynamic piezoelectric effect. Experimental observations confirming such predictions are given.

ISSN:0021-8979    

DOI:10.1063/1.345562

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.346113

出版商:AIP    

年代:1990

数据来源: AIP