A Simple Current Collapse Measurement Technique for GaN High-Electron Mobility Transistors

Current collapse in GaN high-electron mobility transistors (HEMTs) is a temporary reduction of drain-current immediately after the application of high voltage. Current collapse limits the output power of the device at high frequencies. Oftentimes, a signature of device degradation is an increase in current collapse. In order to improve the GaN HEMT performance and reliability, understanding the current collapse phenomenon is critical. In this letter, we propose a simple technique to measure current collapse that utilizes common dc device characterization equipment. Our proposed technique produces consistent measurements when compared with the conventional but highly specialized pulse technique. Underlying our proposed technique is the recognition that in a transient current measurement, the traps that produce current collapse have detrapping time constants on the order of seconds.