Abstract
Surface traps on GaN-based HEMTs (high-electron-mobility transistors) usually result in the increase of channel on-resistance. It becomes worsen when short pulses are applied during high-frequency and high voltage switching. Here we present a dual-gate transistor structure to suppress the dynamic on-resistance increase. The auxiliary gate under a proper fixed voltage is able to induce additional electrons to compensate the channel carrier loss during main gate switching, leading to a lower dynamic on-resistance. In this work, we benchmarked the fundamental electrical properties of both single-gate and dual-gate HEMTs. We further extracted the dynamic electrical properties by stressing the devices with short pulses. The results suggest a significant mitigation of current collapse of a dual-gate HEMT under a proper bias applied on the auxiliary gate electrode. The physical mechanism based on the charge distribution in the channel is employed to explain the observations.
Highlights
The AlGaN/GaN high-electron-mobility transistors (HEMTs) possess advantages such as wide-bandgap, large-breakdown field and large-electron mobility, making them a promising candidate for future performance driven power electronics which switching frequency, power density, and conversion efficiency are the main parameters of concern [1]–[3]
As for DG-HEMTs, Vth is −3.76 and −3.60 V, when the main gate bias was applied on GL and GR, respectively
The more negative Vth of the DG-HEMT, with either GR-drive or GL-drive, is attributed to additional carriers induced by the floating gate [14]
Summary
The AlGaN/GaN high-electron-mobility transistors (HEMTs) possess advantages such as wide-bandgap, large-breakdown field and large-electron mobility, making them a promising candidate for future performance driven power electronics which switching frequency, power density, and conversion efficiency are the main parameters of concern [1]–[3]. One of the gates is used to drive the device and the other acts as an auxiliary electrode to provide additional electrons in the channel so that current collapse is suppressed at the moment device switched-on. Literature survey suggests that two different gate metals connected together [11]–[13] or separated from each other [14], [15] between source and drain electrodes can change the device electrical properties, such as drain current levels and threshold voltage [11]–[13], and improvement of current collapse due to the re-distribution of the electric field in the channel. To explore the physical root cause of current collapse, there were reports using the additional gate to probe the surface trap distribution [16], [17] We, in this current work, actively bias both gate electrodes so that the electric field in the channel is re-distributed and additional carriers are provided during switching. Physical mechanisms to explain the mitigation of current collapse are discussed based on the charge distribution in the channel
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