Enhancement-mode AlGaN/GaN HEMTs fabricated by fluorine plasma treatment

Abstract

The fabrication of enhancement-mode AlGaN/GaN HEMTs by fluorine plasma treatment on sapphire substrates is reported. A new method is used to fabricate devices with different fluorine plasma RF power treatments on one wafer to avoid differences between different wafers. The plasma-treated gate regions of devices treated with different fluorine plasma RF powers were separately opened by a step-and-repeat system. The properties of these devices are compared and analyzed. The devices with 150 W fluorine plasma treatment power and with 0.6 µm gate-length exhibited a threshold voltage of 0.57 V, a maximum drain current of 501 mA/mm, a maximum transconductance of 210 mS/mm, a current gain cutoff frequency of 19.4 GHz and a maximum oscillation frequency of 26 GHz. An excessive fluorine plasma treatment power of 250 W results in a small maximum drain current, which can be attributed to the implantation of fluorine plasma in the channel.

DC and RF performance of lateral AlGaN/GaN FinFET with ultrathin gate dielectric

“…This shift depends on the radio frequency (RF) power and exposure time to the plasma. Thus E-mode operations are obtained by charge storing, without reducing the channel conductance compare to other approaches [9][10][11]. However, the main drawback with this method is maintaining the V th stable in the thermal steps during the fabrication process.…”