Properties of Si-doped GaN films grown using multiple AlN interlayers

Electrical, optical, and structural properties of Si-doped GaN films grown on multiple AlN interlayers (IL) sandwiched between high-temperature (HT) G aN are presented. We show that as the number of AlN IL/HT GaN layers increa ses, the electron mobility increases in the top Si-doped GaN layer, showing a near doubling from 440 to 725 cm(2) V-1 s(-1). Cross-sectional transmiss ion electron microscopy images reveal a significant reduction in the screw dislocation density for GaN films grown on the AlN IL/HT GaN layers. The sy mmetric and off-axis x-ray linewidths increase as the number of AlN IL/HT G aN layers increase, indicating a greater relative misalignment of the adjac ent HT GaN layers. Photoluminescence spectra of undoped and Si-doped GaN fi lms on the multiple AlN IL/HT GaN layers have small yellow-band intensity. Analysis based on a single-donor/single-acceptor model for the electrical c onduction suggests that the improved electron mobility is the result of a r educed acceptor concentration in the top GaN film and that this acceptor ma y possibly be associated with threading screw dislocations in GaN. [S0003-6 951(99)04546-5].