Performance Limiting Leakage Current Across Ar-Implantation Isolation in AlGaN/GaN Structures for High Power Applications

Electrical characterization of AlGaN/GaN heterojunctions isolated by Ar-implantation identified three conduction regimes. These include an Ohmic regime below 100V associated with conduction across the implanted area itself as well as an exponential regime above 400V associated with a conduction across the buffer or buried interfaces with the substrate. While the extraction of activation energies found an average of roughly 0.85eV for the Ohmic regime, activation energies above 400V were consistent with a Poole-Frenkel conduction mechanism. Time-dependent measurements showed further a capacitive effect for conduction across the buffer at room temperature. Having identified the performance limiting conduction path through the buffer layers, these experimental results can also be used as a tool for epitaxy assessment very early on in the production process.