UBC Theses and Dissertations
Light activated Cl₂ etching of GaAs and optical holographic pattern formation Whitwick, Michael Brian
The photochemical reaction of Cl₂ gas with (100) GaAs was studied in this work. Thermal effects due to light induced heating of the GaAs substrate were isolated from photochemical effects. Light induced heating was calculated and the corresponding photothermal Cl₂ etching of GaAs was accounted for. The temperature dependence of the photochemical etch rate was examined. The light-induced etch rate potentially follows an Arrhenius temperature dependence with an activation energy of 0.161 eV. Near 200°C the light-induced etch rate does not increase with increasing temperature. The photochemical etch rate was found to depend linearly on intensity. A possible explanation for the temperature dependence of the photochemical etch rates is presented. It is proposed that the desorption of Ga Cl₃ is the important mechanism in the photochemical Cl₂-GaAs etch. GaCl₃ is photodesorbed with illumination, which increases the rate of etching.