A Parametric Technique for Trap Characterization in AlGaN/GaN HEMTs
S. J. Duffy, B. Benbakhti, Weidong Zhang, K. Ahmeda, K. Kálna, M. Boucherta, M. Mattalah, Hassane Ouazzani Chahdi, N. Bourzgui, A. Soltani
Abstract
A new parametric and cost-effective technique is developed to decouple the mechanisms behind current degradation in AlGaN/GaN high-electron mobility transistors (HEMTs) under a normal device operation: self-heating and charge trapping. Our unique approach investigates charge trapping using both source (IS) and drain (ID) transient currents for the first time. Two types of charge-trapping mechanisms are identified: 1) bulk charge trapping occurring on a timescale of less than 1 ms and 2) surface charge trapping with a time constant larger than a millisecond. Through monitoring the difference between IS and ID, a bulk charge-trapping time constant is found to be independent of both drain (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> ) and gate (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">GS</sub> ) biases. Surface charge trapping is found to have a much greater impact on slow degradation than bulk trapping and self-heating. At a short timescale (<; 1 ms), the RF performance is mainly restricted by both bulk charge-trapping and self-heating effects. However, at a longer time (>1 ms), the dynamic ON-resistance degradation is predominantly limited by surface charge trapping.