Nanoscale luminescence spectroscopy of defects at buried interfaces and ultrathin films

Abstract

Low energy electron-excited nano-luminescence (LEEN) spectroscopy provides electronic band gap, confined state, and deep level trap information from semiconductor surfaces and interfaces on a nanometer scale. Correlation of luminescence features with their spatial location inside a growth structure—either depth wise or laterally—also provides information on the physical origin and growth dependence of the electronically active defects that form. LEEN spectroscopy of localized states illustrates this approach for a representative set of III–V nitride interfaces, including metal-GaN Schottky barriers, GaN/InGaN quantum wells, GaN ultrathin films, AlGaN/GaN pseudomorphic heterostructures across a single growth wafer, and GaN/Al2O3 interfaces. In each case, electronic properties are sensitive to the chemical composition, bonding, and atomic structures near interfaces and in turn to the specifics of the growth process.