Heterojunction Materials and Characteristics.

摘要

Molecular beam epitaxy was used to provide samples for extremely abrupt GaAs/GaA1As heterojunctions for AES profiling of the interface and ESCA measurements of the A1As valence band structure. The latter samples consist of MBE A1As layers covered with 50A to 100A of GaAs as protection against oxidation. MBE growth of n-type A1GaAs was studied also. N-type A1GaAs was produced although all the n-type conducting A1GaAs layers grown by MBE had low activation of the dopant (2%-40%) and relatively low room temperature mobilities (650 cu cm sq /v-sec to 1200 cu cm sq /v-sec). It was found that A1 source design and background vacuum were important influences on the quality of n-type A1GaAs produced. Some initial measurements were made on the electrical properties of n-GaAs/n-A1GaAs and n-GaAs/n-A1GaAs/n-GaAs structures. I-Vf measurements on n-n structures at room temperatue showed no deviations from ohmic behavior, while C-V measurements on n-n-n structures were hampered by trapping effects in the A1GaAs. (Author)