Interface structures of III–V semiconductor heterostructures

Abstract

ABSTRACT:We report first-principles calculations of the electronic and geometric structure of the (110) cross-sectional surfaces on InAs/GaSb superlattices and compare the results to scanning tunneling microscopy images of filled electronic states. We also study the atomic scale structure of (001) interface surfaces and the adsorption of deposited atoms on these surfaces to simulate the process occurring during the heterostructure growth. In both the predicted and measured images the InAs (110) surfaces appear lower than GaSb, a height difference we show is caused primarily by differences in the electronic structure of the two materials. In contrast, local variations in the apparent height of (110) surface atoms at InSb-or GaAs-like interfaces arise primarily from geometric distortions associated with local differences in bond length. We further observed that both Ga-and Sb-terminating (001) surfaces showed dimerization of surface atoms. Ga-terminating (001) surfaces exhibited substantial buckling of surface atoms while Sb-terminating (001) surfaces did not show appreciable buckling. The adsorption of arsenic atoms occurred preferably at the bridge sites between the dimerized Sb atoms on Sb-terminating (001) surfaces. Indium atoms, on the other hand, were observed to have somewhat equal probabilities to be adsorbed at a few different sites on Ga-terminating (001) surfaces. Our calculated energies for atomic intermixing indicate that anion exchanges are exothermic for As atoms on Gaterminating (001) interfaces but endothermic for In atoms on Sb-terminating (001) interfaces. This difference may explain why GaAs interfaces are typically more disordered than InSb interfaces in these heterostructures. Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. We report first-principles calculations of the electronic and geometric structure of the (110) cross-sectional surfaces on InAs/GaSb superlattices and compare the results to scanning tunneling microscopy images of filled electronic states. We also study the atomic scale structure of (001) interface surfaces and the adsorption of deposited atoms on these surfaces to simulate the process occurring during the heterostructure growth. In both the predicted and measured images the InAs (...

Arsenic cross-contamination in GaSb/InAs superlattices

“…In this filled state tunneling image, the ''dark'' (i.e. topographically lower) regions represent InAs layers and the ''bright'' regions the GaSb layers [5,7,10]. Note that the few brightest, cluster-like structures on the surface correspond to small, monolayer-height islands resulting from an imperfect cleave.…”

Controlling interfacial disorder and strain of W-structured type-II superlattices using As2 flux

“…Increasing the As flux tends to suppress island formation during InAs growth, promoting smoother InAs growth surfaces [18], and therefore smoother and more homogeneous InGaSb-on-InAs interfaces (i.e., smaller D and larger L). However, higher As fluxes also promote As incorporation into antimonide layers [10,12,19,20], which will tend to increase the random As component of the interfacial layer, consistent with the slight decrease in the correlation length at the highest relative As flux. The structure of the InAs-on-InGaSb interfaces is consistent with the competing effects of the Sbrich antimonide growth surface and As incorporation into that surface [10,11,[19][20][21].…”

AlAs-in-AlSb digital alloy superlattice morphology versus growth temperature

“…In our case, the Al flux was kept constant, with only the anion flux modulated, so there were no anion ''soaks'' to promote such exchange. However, even in the absence of growth interrupts, As-for-Sb exchanges can occur across the interface for thermodynamic reasons; for the GaSb/InAs system, As-for-Sb exchange (to create GaAs) is actually exothermic [14,19]. These effects may contribute to additional atomic-scale disorder at the interfaces that is independent of roughness associated with the growth front morphology.…”