Published online by Cambridge University Press: 10 February 2011
A chemical bath deposition process was used to grow thin (25–200 Å) films of cadmium sulfide on (100) InP from an aqueous solution of ammonium hydroxide, cadmium sulfate, and thiourea at 75–85 °C. Reflection high energy electron diffraction (RHEED) and transmission electron microscopy (TEM) show that ˜30 Å films are amorphous, while thicker films exhibit a cubic polycrystalline microstructure, with a preferred orientation in the [110] direction. X-ray photoelectron spectroscopy (XPS) shows the CdS treatment both removes the native oxides of InP and forms a stabilizing layer which protects the substrate from re-oxidation. Quasistatic capacitance-voltage response of MIS capacitors on InP, with a CdS layer between the insulator and substrate, exhibits well defined regions of accumulation, depletion, and inversion, indicating a high-quality interface region. An experimental Cmin/Cox, value of 0.28 was obtained, compared to the theoretical value of 0.07. The density of interface states (Dit) was reduced from 1012 to 1011 eV−1cm−2 after CdS treatment when calculated by the high-low method. InP MISFETs fabricated using CdS interlayers showed greatly enhanced device performance over untreated MISFETs.