INVESTIGATION OF CHEMICAL WET-ETCH SURFACE MODIFICATION OF GA0.5IN0.5P USING PHOTOLUMINESCENCE, X-RAY PHOTOELECTRON-SPECTROSCOPY, CAPACITANCE MEASUREMENTS, AND PHOTOCURRENT-VOLTAGE CURVES

Epitaxial Ga0.5IN0.5P films, deposited lattice-matched to GaAs by atmo spheric pressure organometallic vapor phase epitaxy, were subjected to various wet-etching processes and the resulting surface was character ized. The steady-state photoluminescence (PL) peak intensity was found to increase 5-fold with some etches, indicating lowered surface recom bination rates as a result of etching. Average PL decay times estimate d from time-resolved photoluminescence studies also exhibited a corres pondingly significant enhancement. Capacitance-voltage and photocurren t-voltage measurements were carried out to investigate changes in ener getics of the band edges or alteration in kinetics as a result of the treatments. High resolution X-ray photoelectron spectroscopy revealed a variation of the oxidized species of P, Ga, and In on the surface wi th etching and were correlated to the PL results. The amount of oxidiz ed material on the surface was lowered after etching in concentrated H 2SO4, 1:20:1 HCl:CH3COOH:H2O2, and 1:20:1 HCl:H3PO4:H2O2 and concurred with observations of a higher steady-state PL intensity and longer ca rrier lifetimes. A nitric acid or aqua regia etch on the other hand yi elded an oxide-rich surface with diminished PL.