Anisotropic etching of GaAs using a hot Cl2 molecular beam

Anisotropic etching of GaAs(100) is performed using a hot Cl2 molecular beam produced by free expansion of gas heated in a furnace. The etch rate is 1.5 μm/min at a furnace temperature of 800 °C and a substrate temperature of 120 °C. An aspect ratio of ten and an almost smooth bottom surface are obtained under this condition.