ANALYSIS OF GAAS SUBSTRATE REMOVAL ETCHING WITH CITRIC ACID-H2O2 AND NH4OH-H2O2 FOR APPLICATION TO COMPLIANT SUBSTRATES

New properties associated with selective substrate removal have been o bserved in the application of this technique to GaAs thin film complia nt substrates. Citric acid- and NH4OH-based etches are used to selecti vely etch the GaAs substrate and stop on an AlAs layer. The AlAs stop- etch layer is transformed into a layer that is almost twice as thick a s the original layer, mismatched to the remaining GaAs epilayer, and h as a refractive index around 2.0. Replacement of the single AIAs stop etch layer with multiple thin AlGaAs stop etch layers is proposed to a lleviate this problem.