The reaction of gallium arsenide {100} with molecular and atomic bromine was studied at temperatures between 100 and 225°C and at pressures of bromine between 0.1 and 40 Torr. Samples of GaAs were placed on a silicon platform within a Pyrex reactor flow system and the etch rate was determined by profilometry or weight change of the sample. Atomic bromine was produced by a 2450 MHz microwave discharge and the samples were etched downstream. The atomic concentration was measured by an isothermal calorimetric detector.
Pressure dependence studies for molecular Br₂ etching showed that below 1-2 Torr of bromine, a first order reaction was rate-limiting whereas above this pressure a half order reaction was rate-limiting. Temperature dependence studies for the low pressure and high pressure regimes gave activation energies and pre-exponential values for the two respective rate controlling reactions. The first order reaction was found to have an activation energy of 29.2 ±4.0 kJ mol⁻¹ and a pre-exponential value of (3.4 ± 4.4) x 10²¹ molecule cm⁻² s⁻¹ Torr⁻¹. The activation energy for the half order reaction was found to be 8.4 ± 0.7 kJ mol⁻¹ with a pre-exponential of (6.4 ± 1.3) x 10¹⁸ molecule cm⁻² s⁻¹ Torr⁻¹⁄².
The activation energy for atomic etching was calculated to be 12.9 ± 0.9 kJ mol⁻¹ and the pre-exponential, (7.1 ± 2.0) x 10²⁰ atom cm⁻² s⁻¹ Torr⁻¹. / Science, Faculty of / Chemistry, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/29866 |
| Date | January 1990 |
| Creators | Salusbury, Ian McKenzie |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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