Dislocation-filtering AlInSb buffer layers for InSb quantum wells—Analysis by high-tilt bright-field and dark-field TEM

We have investigated the effect of an AlInSb interlayer on dislocation filtering, aiming at a further improvement in the performance of InSb quantum well devices that are often grown on a largely lattice-mismatched substrate, such as Si and GaAs, via an AlInSb buffer layer. Transmission electron microscopy (TEM) analyses under high-tilt bright-field (HTBF) and high-tilt dark-filed (HTDF) conditions provide the capabilities of (A) analyzing the reaction between threading dislocations (TDs) and misfit dislocations (MDs) and (B) measuring local TD and MD densities around an interface which is embedded deep into an epilayer. An HTBF-TEM analysis shows that 50% of TDs are eliminated at an (0 0 1) Al0.25In0.75Sb/Al0.10In0.90Sb interlayer interface where the TD density was originally 8.6×109 /cm2. Twenty three percent of the mechanical strain at such an interface was relaxed by a MD density of 1.6×105 /cm. In this study, the detailed practical procedures of HTBF- and HTDF-TEM analyses are also discussed.