Exposure of AlGaAs Window Layer

A highly dopedp+-GaAs contact layer, typically 300-600nm thick, is included over the p-AlxGai_xAs window layer (x ~ 0.8-0.9). This exhibits high absorption and recombination and must be removed between the gridlines. A self-aligned selective wet etch (e. g. СбН807-Н202 or NH4OH-H2O2 for selective etching of GaAs over AlxGa1_x As) is generally employed for this purpose.