POTENTIAL-INDUCED CHANGES IN THE SURFACE-MORPHOLOGY OF (100)N-INP SAMPLES PHOTOELECTROCHEMICALLY ETCHED

The surface morphology of (100) n-InP samples photoelectrochemically e tched in homogeneous white light was studied. The photoelectrochemical etches were strongly anisotropic and resulted in the production of mi crostructures, the size and shape of which depended on the charge dens ity and applied potential, respectively At more positive etching poten tials V-grooves aligned along the [0 (1) over bar 1] axis were formed, delineated by the (111) and (1<(11)over bar>) indium etch stop planes , whereas etching at more negative potentials resulted in the formatio n of rectangular shaped pits oriented along the [011] axis. These pits were composed of large (111) and (1<(11)over bar>) indium etch stop p lanes and a more complex stepped structure which was analyzed in detai l. We explain the relationship between the etching potential and the r esulting structures by calculating the distribution of photogenerated minority carriers in the region below the surface of the semiconductor .