Experimental evidence for dislocation-related gettering in metamorphic InP∕InGaAs high electron mobility transistor (HEMT) structures on GaAs substrate

Abstract

The thermal stability of metamorphic InP∕InGaAs high electron mobility transistor (HEMT) structures on GaAs substrate subjected to rapid thermal annealing (RTA) has been systematically investigated in the temperature range of 350–700°C. Based on the characterization of the electrical and optical properties, we observed that the metamorphic structures, in which the HEMT structures are grown on a metamorphic stain-relief buffer, exhibit better thermal stability when compared to a lattice-matched structure (control) at annealing temperatures higher than 550°C. An improved photoluminescence (PL) intensity in the temperature range of 550–650°C for metamorphic samples was observed. This behavior is absent in lattice-matched control structures. The better thermal stability and enhanced PL intensity at high RTA temperatures observed in metamorphic structures can be explained as a consequence of the possible dislocation-related gettering effect due to the presence of the dislocation network (gettering sink) located immediately beneath the device zone. Our experimental observation may partially ease the potential concerns about the thermal stability of metamorphic HEMTs.