Dopant Selective Photoelectrochemical Etching of GaAs Homostructures

Abstract

We have examined the etch selectivity of homostructures of 1 ~m of n+GaAs (2 x 10 TM cm -3) on both a nonintentionally doped (NID) substrate and a p*GaAs (2 x 1018 cm -3) substrate. Samples were etched at 1.38 W/cm 2 in a 1:20 HCl:H20 elec- trolyte over a bias range from -0.5 to +0.5 V. The selectivity of the n§ structure is extremely high at >-(15,000:1). The selectivity of the n§ GaAs structure is significantly less, on the order of (30:1). The relative etch selectivity of the latter structure has a strong dependence on applied bias.