SURFACE CONCENTRATIONS OF INDIUM, PHOSPHORUS, AND OXYGEN IN INDIUM-PHOSPHIDE SINGLE-CRYSTALS AFTER EXPOSURE TO GAMBLE SOLUTION

The surface of indium phosphide single crystals exposed to synthetic lung fluid (Gamble solution) has been investigated. An oxygen depth profile, obtained by employing the 3.034-Mev resonance in the elastic scattering of alpha particles from O-16, detected oxygen at maximum concentrations of 24% in a layer 1000 angstrom thick. O:In and O:P ratios were found to increase with prolonged exposure time as determined by angle-resolved XPS, although binding energies and peak fwhm's remained relatively constant. The surface concentration of indium was found to be decreased in this 1000-angstrom-thick layer. In3+ was detected at parts per billion levels in the Gamble solution, confirming that indium was leached from the InP surface. The similarity of P:In ratios at all lengths of exposure suggests that phosphorus was also leached by the Gamble solution.