Improved Molecular Beam Epitaxy for Fabricating AlGaN/GaN Heterojunction Devices

Abstract

Listen

Translate article

The polarity-control technology for Ga-polar GaN with rf plasma nitrogen-source molecular beam epitaxy (RF-MBE) was established. Inserting high-temperature grown AlN multiple intermediate layers (HT-AlN-MIL) into MBE-grown GaN at 750 °C suppressed the propagation of dislocations into upper GaN, and the electrical and optical properties were improved. The HT-AlN-MIL was deposited on GaN templates grown by metal organic chemical vapor deposition (MOCVD), followed by GaN grown by MBE. The dislocations with screw character in MBE-grown GaN were reduced by about two orders of magnitude compared to those of the bottom GaN template, which produced the step-like surface morphology for MBE-grown GaN. To demonstrate the capability of MBE in heterojunction control, GaN/AlN double barrier resonant tunneling diode (RTD) structures were fabricated to show the negative differential resistance with a peak-valley ratio of 3.1.