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Kinetics of buffer-related RON-increase in gan-on-silicon mis-hemts

Abstract:

This letter reports an extensive analysis of the charge capture transients induced by OFF-state bias in double heterostructure AlGaN/GaN MIS- high electron mobility transistor grown on silicon substrate. The exposure to OFF-state bias induces a significant increase in the ON-resistance (Ron) of the devices. Thanks to time-resolved on-the-fly analysis of the trapping kinetics, we demonstrate the following relevant results: 1) Ron-increase is temperature- and field-dependent, hence can significantly limit the dynamic performance of the devices at relatively high-voltage and high temperature (100°C-140°C) operative conditions; 2) the comparison between OFF-state and back-gating stress indicates that the major contribution to the Ron-increase is due to the trapping of electrons in the buffer, and not at the surface; 3) the observed exponential kinetics suggests the involvement of point-defects, featuring thermally activated capture cross section; and 4) trapping-rate is correlated with buffer vertical leakage-current and is almost independent to gatedrain length.