CADMIUM-SULFIDE SURFACE STABILIZATION FOR INP-BASED OPTOELECTRONIC DEVICES

Thin layers of chemical bath deposited cadmium sulfide were used to im prove the surface and interface properties of InP and its latticed-mat ched III-V compounds. X-ray photoelectron spectroscopy indicates chemi cal reduction of surface oxides and the prevention of subsequent group III or V oxide formation. Photoluminescence spectra, measured between 1.0 and 1.3 mu m, indicate a dramatic reduction in phosphorus vacanci es following CdS treatment. Metal-insulator-semiconductor capacitors f abricated on n-type InP substrates with CdS interlayers display near-i deal quasi-static response and interface-state densities in the low 10 (11)/eVcm(2) range. Thin CdS layers were used to passivate the surface of InAlAs/InGaAs high electron mobility transistors (HEMTs) and metal -semiconductor-metal (MSM) photodetectors. After CdS treatment, Schott ky diode barrier heights of 0.6 eV were regularly obtained. For HEMTs, drain-to-gate current ratios of 8 x 10(4) were observed after CdS tre atment. For a new backside illuminated MSM design, the dark current of CdS-treated samples was reduced three orders of magnitude to below 1 nA.