摘要:

The metastable nature of molecular‐beam epitaxy grown CdS layers was studied. Undoped CdS layers were grown on (100) GaAs substrates/(100) ZnSe buffer layers, and crystal structures were characterized by x‐ray diffraction and transmission electron microscopy. Undoped films showed both zincblende and wurtzite structures depending on the growth condition; higher substrate temperatures and smaller VI/II beam intensity ratios preferentially form wurtzite structures. The Ga doping significantly affected the crystal structure and Ga doped CdS layers preferentially formed wurtzite structures. Thermal instability of the CdS film was observed through variousexsituannealing experiments. The wurtzite structure phase was developed from the zincblende structure CdS layers by thermal annealing where the annealing temperature was lower than the growth temperature.

ISSN:1071-1023    

DOI:10.1116/1.588863

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We report the successful molecular‐beam epitaxy growth of high quality CdTe/Cd1−xMgxTe quantum wells (x=0.27–0.52) on GaAs (100) and (111)Bsubstrates. The effectiveness of the two different buffer layers for providing nearly lattice‐matched templates were verified by x‐ray diffraction and photoluminescence. Optical properties of excitons in the above quantum wells were investigated. It is observed that, for the (100) sample, the exciton displays double peaks, the peak splitting originating from exciton localization on the monolayer fluctuation of the quantum well width. Our experiments indicate that the influence of such fluctuations can be reduced, and interfaces of exceptional perfection can be obtained by growth of the CdTe/CdMgTe quantum well structures on GaAs (111)B‐oriented substrates or by a combined growth of conventional molecular‐beam epitaxy and migration‐enhanced epitaxy on GaAs (100)‐oriented substrate. The photoluminescence spectra indicate that significant reduction of the influence of the monolayer fluctuation was indeed accomplished by these procedures.

ISSN:1071-1023    

DOI:10.1116/1.588864

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Molecular beam epitaxy of Si1−xGexalloys, grown on (100)‐oriented Si substrates by using gaseous Si2H6and GeH4as sources in the alloy composition rangex<0.33, and on (100)‐oriented and (100)‐misoriented Si substrates by using gaseous Si2H6and solid Ge as sources over the alloy composition range (0≤x<1), has been studied. From the observed growth rates as a function of composition it is evident that the presence of Ge tends to decrease the Si incorporation rate. Our results indicate growth via adatom migration to kink sites in a dissociative chemisorption process.

ISSN:1071-1023    

DOI:10.1116/1.588865

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Facet formation and competition in selective epitaxial growth (SEG) of Si on SiO2−masked nanometer growth windows were studied experimentally and theoretically in gas source molecular beam epitaxy. The windows were patterned along [110] on Si(100) substrates. Mass accumulation around the edge of the SEG mesa top surface was observed and believed to be due to the interfacet mass transport from sidewalls to the top surface. Sidewall facet evolution from the initial (311) to (111) was observed. The facet evolution is due to the growth rate anisotropy among (100), (311), and (111). The interfacet mass transport is believed to affect growth rate of each facet and increase the growth rate anisotropy. As a result, it controls the size dependence of SEG growth rate and promotes the facet evolution. A theoretical model has also been developed for modeling the facet competition and evolution. Both the interfacet and intrafacet surface migration processes were taken into account in the model. The simulation results explain our experimental observations and provide an improved understanding of the facet growth on patterned substrates.

ISSN:1071-1023    

DOI:10.1116/1.588866

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A new class of Si‐based quantum confined geometry is demonstrated using a combination of oppositely strained layers grown on a step‐graded relaxed SiGe buffer. The role of heterointerfaces is revealed as the controlling mechanism of the exciton localization, which results in enhanced no‐phonon transition intensity.

ISSN:1071-1023    

DOI:10.1116/1.588867

出版商:American Vacuum Society    

年代:1996

数据来源: AIP