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在SiC衬底上制备了栅长为110 nm、漏源间距为2μm的W波段AlGaN/GaN高电子迁移率场效应晶体管(HEMT),分析了SiN钝化对器件直流和射频特性的影响。研究发现:100 nm SiN钝化可显著提升器件的漏源饱和电流及峰值跨导,漏源饱和电流从1.27 A/mm增加至1.45 A/mm(Vgs=1 V),器件峰值跨导从300 m S/mm提升至370 m S/mm,这是由于Si N钝化显著提高了AlGaN/GaN异质结材料沟道电子浓度。此外,SiN钝化可有效抑制器件电流崩塌,显著改善器件直流回扫特性。然而,由于沟道电子浓度增大,钝化后器件中短沟效应增强,器件夹断特性变差。此外,SiN钝化后W波段AlGaN/GaN HEMTs的射频特性得到显著改善,器件的电流增益截止频率从钝化前的33 GHz提升至107 GHz,最高振荡频率从钝化前的65 GHz提升至156 GHz。
A W-band AlGaN / GaN HEMT with a gate length of 110 nm and a drain-source spacing of 2 μm was fabricated on a SiC substrate. The influence of SiN passivation on DC and RF characteristics of the device was analyzed. The results show that 100 nm SiN passivation can significantly improve the drain-source saturation current and peak transconductance. The drain-source saturation current increases from 1.27 A / mm to 1.45 A / mm (Vgs = 1 V) The m S / mm was raised to 370 m S / mm because Si N passivation significantly increased the channel electron concentration of the AlGaN / GaN heterojunction material. In addition, SiN passivation can effectively suppress the device current collapse, significantly improve the device DC flyback characteristics. However, due to the increase of the channel electron concentration, the short-channel effect in the passivated device is enhanced, and the device pinch-off characteristics are deteriorated. In addition, the RF characteristics of W-band AlGaN / GaN HEMTs after SiN passivation were significantly improved. The current gain cut-off frequency of the device was raised from 33 GHz before passivation to 107 GHz and the maximum oscillation frequency was raised from 65 GHz before passivation to 156 GHz.