Long-storage-time MIS capacitors formed on InSb films grown by MOCVD

Abstract

Metalorganic chemical vapor deposition (MOCVD) for epitaxially grown InSb has been explored for infrared (IR) detector applications that incorporate a metal-insulator-semiconductor (MIS) device structure. InSb epilayers were attempted on InSb substrates with the (111)A, (111)B, and (100) surface orientations using an MOCVD process at 450° C. SiO₂ insulator films were formed on these epilayers using a photon-assisted CVD process. Successful MIS fabrication was most reproducible on the (100) surface, where a large-area, featureless morphology was routinely attained. MIS devices were characterized by standard analyses of capacitance-voltage (C-V) and transient-capacitance (C-t) measurements as a function of temperature between 77 and 110 K. Epilayers that had net donor concentrations of about 1 to 3 × 10¹⁵ cm⁻³, the lowest achieved, demonstrated improvement for IR detector applications. For example, MIS storage times in deep depletion at 77 K exceeded 150 ms, about an order of magnitude longer than those typically measured in control samples of commercially available InSb grown by the Czochralski process. Longer storage times correlated with enhanced generation lifetimes. These relative improvements are attributed to a lower density of thermally induced defects in the epilayer material.