Surface chemical reactions on In0.53Ga0.47As

Abstract
Dark currents on In0.53Ga0.47As mesa photodiodes can be reduced significantly by treating the surfaces with H2SO4:H2O2:XH2O (10≤X≤500) instead of the usual bromine‐methanol etch. Using spectroscopic ellipsometry we show that peroxide etches form porous amorphous As or oxide overlayers according to whether the pH values are less than or greater than ∼3. The identity of these overlayers is established by their dielectric response and chemical reactivity.