Effects of Defects on Metal-Insulator-Semiconductor Properties of HgCdTe Films Grown by Liquid Phase Epitaxy

Abstract

ABSTRACTA comprehensive study of all materials parameters influencing metal-insulator-semiconductor (MIS) properties of n-type HgCdTe films grown by liquid phase epitaxy from tellurium rich melts was conducted. When the epitaxy process was optimized to grow films free of inclusions and terracing, the first indications of the MIS properties to be expected could be obtained from the temperature dependence of the Hall electron mobility.Films displaying an anomalous dependence of the Hall mobility on temperature yielded non-classical low frequency MIS properties with little or no measurable ‘dark’ storage times (< 2×10−6 second). The MIS performance of these films appeared relatively independent of other materials parameters; remaining, for example, virtually unaffected by the film dislocation density changing between 5×104 and 2 × 106/cm2.Films displaying a classical dependence of the Hall mobility on temperature yielded drastically improved classical high frequency MIS properties. For these films, the MIS performance appeared almost exclusively dependent on dislocation density levels as long as the donor density remained lower than 1×1015/cm3. The dark storage time of classical films increased continuously with decreasing dislocation density levels, rising to 100µsec for a dislocation density level of 1 × 105/cm2 for materials with a 77°K cutoff wavelength of 10.5 µm. A simple monotonic relationship could be established between the MIS performance parameters and the dislocation density over the entire measurement span: from 5×104 to 2.5×106/cm2.