Two-terminal electroluminescence of AlGaN/GaN high electron mobility transistors

Electroluminescence (EL) characteristics from reverse-biased Schottky barrier diode are investigated on AlGaN/GaN high electron mobility transistors (HEMT) with different structures. Light emission from devices under high voltage or with high gate leakage current exhibit bluish or reddish color, suggesting different emission mechanism. No obvious EL is observed in AlGaN/GaN/AlGaN double heterostructure at high drain voltage near breakdown. 2D device simulation of the AlGaN/GaN HEMT at high drain voltage shows distinct separation of electrons and holes distribution, eliminating the possibility of direct band-to-band transitions. By comparing the EL image from front side and back side of the wafer, the manufacturing related problems as well as the location of material defects are detected.