THE ETCHING OF INP BY ACIDIC IODINE SOLUTIONS - A KINETIC AND ELECTROCHEMICAL STUDY

The etch rate of monocrystalline p- and n-InP in acidic I-2 + I- solut ions was measured as a function of several variables, using a flow cel l setup. Electrochemical measurements were performed in darkness and u nder illumination. Both cathodically for p-type and anodically for n-t ype, enhancement of the limiting photocurrent was observed when adding iodine to the indifferent electrolyte solution. From combined etch ra te and electrochemical data, the stoichiometry of the surface etch rea ction was deduced, and it was established that a sequential chemical e tching mechanism operates. It was shown that interaction occurs betwee n chemical etching of the semiconductor by iodine and anodic dissoluti on when holes are available at the surface. The etch rate of the (111) face was found to be lower than that of the ((1) over bar (1) over ba r (1) over bar) and (100) faces. In most cases, the kinetics of the et ching reaction were clearly correlated to the resulting morphology and to the shape of the etching profiles at mask edges.