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Title: Dry etched III-V semiconductors for nanoelectronics
Author: Cheung, Rebecca Mei Kwan
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1990
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The purpose of this work was to try to identify the amount, degree and physical nature of the damage caused on both the surface and sidewalls of reactive ion etched GaAs and AlGaAs nanostructures using a variety of complimentary characterisation techniques, and to develop low damage high resolution dry etch processes for GaAs and AlGaAs. The gases investigated included SiCl4, CH4/H2 and CCl2F2/He. Two new methods of etching GaAs anisotropically by magnetron radio-frequency and electron cyclotron resonance radio-frequency reactive ion etching employing CCl2F2/He, and the use of a novel gas mixture CH4/H2 to reactive ion etch GaAs in the conventional radio-frequency mode were developed. It was found to be important to distinguish between surface and sidewall damage, and both were characterised using electrical, optical as well as analytical techniques. In particular, two novel processes were developed using high resolution fabrication techniques for the construction of sidewall Schottky diodes and electron transparent thin wire specimens to allow the amount of sidewall damage to be estimated and its nature to be realised through diode characteristic measurements and transmission electron microscopy analysis. To investigate the surface damage caused after etching, techniques such as Schottky diode performance, integrated band-gap photoluminescence, Raman scattering and X-ray photoelectron spectroscopy were employed; and for the first time, the usefulness of specular X-ray reflectivity for the identification of surface damage was explored. Sidewall damage was examined using room and low temperature conductivity, and low temperature magnetoconductance of n+ GaAs quantum wires, sidewall Schottky diode characteristics and transmission electron microscopy on thin wire specimens. The dependence of surface and sidewall damage on etch time and etch power was also studied.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available