Synthesis and Properties of Mismatched Heterojunction/Substrate Interfaces
Annual rept. 27 Aug 1991-1 Aug 1992,
CALIFORNIA UNIV SAN DIEGO LA JOLLA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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Unstrained Inx,Ga1-xAs and InyAl1-yAs layers and heterostructures lattice matched to each other but mismatched with respect to their GaAs substrates were grown by molecular beam epitaxy using compositionally step graded buffer layers to relax the mismatch strain by more than 90 and their structure, composition, electrical and optical properties were investigated. For x 0.3 the buffer layer is stabilized by dislocation loops. Two-dimensional electron gas in modulation doped heterostructures exhibit a 300 K mobility rising from 9X103 cm2V-s for x 0.3 to 1.1X104 cm2V-s for x 0.45 and an estimated conduction band offset, Delta Ec - 0.67 times the bandgap difference between the quantum well and the barrier layer.