Defect Characterization of Molecular Beam Modular Epitaxially Grown HgCdTe Samples.

摘要

This report provides an overview of defect characterization techniques of epitaxially grown mercury cadmium telluride (HgCdTe) wafers. The development of good HgCdTe based detectors requires high quality semiconductor material. Growth conditions, choice of substrate, and overall cleanliness of the entire procedure all have a major impact on material quality. The types of defects that can be observed include craters, surface hillocks, dislocations, precipitates, bumps, and post-growth scratches due to human error. While high quality, low dislocation density (<105 cm-2) HgCdTe can be grown on lattice matched cadmium zinc telluride (CdZnTe) substrate, these substrates are expensive and have limited area. Lattice-mismatched silicon substrates are available in large area and low cost, but result in higher dislocation density (>106 cm-2). These defects hinder device performance. The goal of epitaxial growth is to have the least amount of defects possible. The project objective was to characterize various defects in HgCdTe films grown on Si substrates and recognize their importance.