Extraction of effective trap density and gate length in AlGaN/GaN HEMTs based on pulsed I-V characteristics

Reliability issues such as degradation of DC, transient, and RF characteristics have been intensively investigated in AlGaN/GaN HEMT applications. The instability of AlGaN/GaN HEMT operations is attributed to modification in electrical behavior of trapping centers induced during the material growth and device fabrication, and/or introduction of new traps, caused by electrical/thermal stress. However, it has been difficult to analyze accurate trapping density and effective gate length under device operation since electron capture and emission are varied depending on bias condition and trap position/energy level. Thus, precise monitoring methodology for trapping effects is required. In this paper, we report a simple method to extract effective trap density based on pulsed I-V measurements under different quiescent bias (QB) conditions with a very short pulse width.