Molecular beam epitaxy of CdTe on GaAs substrates and HgCdTe on CdTe/GaAs alternate substrates
Two aspects of molecular-beam epitaxy (MBE) of the infrared sensitive semiconductor Hg{sub 1-x}Cd{sub x}Te were investigated: control of the substrate temperature by infrared pyrometer in addition to rear thermocouple, and improvement of CdTe/GaAs alternate substrates. Pyrometer behavior was recorded while controlling the temperatures of growing Hg{sub 1-x}Cd{sub x}Te with a frontal thermocoupled that contacted their surfaces. These recordings were interpreted in terms of emission and absorption, transmission and reflection, and thin-film interference. Based on these results, temperature control by rear thermocouple was reexamined, resulting in improved technique of that temperature control method as well. A temperature control technique combining both the pyrometer and the rear thermocoupled was developed; and evidence is presented and the rear thermocouple was developed; and evidence is presented for the resulting improvement in crystalline and electrical quality of MBE Hg{sub 1-x}Cd{sub x}Te. Investigations of Hg{sub 1-x}Cd{sub x}Te MBE onto more afforadable, larger, and more rugged CdTe/GaAs alternate substrates focused chiefly on improving the MBE of CdTe onto GaAs. This heteroepitaxy was studied primarily in terms of the influences on CdTe crystalline quality of the mismatches in bonding character, lattice spacing, thermal expansion, and charge imbalance between these two zincblende crystals. A novel dual epitaxial relationship, CdTe(331)B/GaAs(112)B and CdTe (112)B/GaAs(112)B, was discovered in these investigations; and the nonparellel orientation proves superior to the parallel orientation and to both orientations of the previously known CdTe(111)B/GaAs(001) and CdTe(001)/GaAs(001) dual epitaxial relationship. A charge imbalance model, applied to these four heterointerfaces, predicts the balancing of that charge by movement of electrons into or out of the heterointerfacial dangling bonds, which exist due to the lattice mismatch.
- Research Organization:
- Illinois Univ., Chicago, IL (United States)
- OSTI ID:
- 106817
- Resource Relation:
- Other Information: TH: Thesis (Ph.D.); PBD: 1993
- Country of Publication:
- United States
- Language:
- English
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