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UBC Theses and Dissertations

Kinetic studies of the reaction of gallium arsenide with molecular chlorine and iodine Wong, Kin-Chung


The GaAs/Cl₂ reaction has been studied at pressures of Cl₂ between 0.10 and 9.0 Torr, and in the temperature range from 90 to 110°C whereas the GaAs/I₂ reaction has been investigated at four temperatures between 270 and 330°C with the I₂ pressure being varied between 0.10 and 1.25 Ton. Both reactions show a linear dependence on the etchant gas pressure in the low pressure region, however, the dependence become nonlinear in the high pressure range. In the case of the Cl₂ reaction, the non linearity was found to be due to the occurrence of a reaction that was half order with respect to the pressure of Cl₂. This behavior was found to be consistent with a "reversible dissociative adsorption" mechanism proposed in earlier studies of the Cl₂ and Br₂ etching of silicon. This mechanism involves the physisorption of the halogen molecule on the semiconductor surface followed by the dissociation of the molecule into chemisorbed atoms, and finally the reaction of these atoms with the surface to yield gaseous products. The first and the half order rate constant for both reactions were determined and represented in the form of the following Arrhenius equations: ...[more text]

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