Study on Trapping Effects in AlGaN/GaN-on-Si Devices with Vertical Interconnect Structures

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In this paper, AlGaN/GaN Schottky gate HEMTs on silicon based on vertical interconnect structures were fabricated and analyzed. The device with a vertical drain interconnect to the substrate shows worse current collapse based on drain lag measurement compared with both the conventional lateral device without vertical interconnect and the device with a vertical source interconnect to the substrate, implying that electrons are trapped in the epilayer due to existence of a vertical electric field. The trapped electrons in the epi and buffer layers introduce a positive shift in the threshold voltage by about 1.5 V together with an increase in the specific on-resistance, but show nearly no effect on the turn-on voltage of the Schottky junction.