Investigation of AlGaN/GaN high electron mobility transistors on Silicon (111) substrates employing multi-stacked strained layer superlattice structures

Abstract

Abstract AlGaN/GaN high electron mobility transistors (HEMTs) on Silicon (111) substrates are grown by using multi-stacked strained superlattices layer structures. Atomic force microscopy, X-ray diffraction and cross-sectional transmission electron microscopy are employed to investigate the structural properties of these AlGaN/GaN HEMT structures. The insertion of AlGaN/AlN strained superlattices layer modified with different numbers of GaN layers is revealed to reduce the pit density and threading dislocation density, resulting in the improvement of epilayer quality. The temperature dependent Hall effect measurements show that the two-dimensional electron gas characteristics are greatly improved by the employed modified superlattices layers in AlGaN/GaN HEMT structures throughout the whole measured temperature range. The superlattices layer engineering is shown to be important for achieving higher carrier mobility (>2340 cm2/V) and sheet carrier density (>8.22 × 1012 cm−2) at room temperature in AlGaN/GaN HEMTs.