漏源间距对AlGaN/GaN HEMT器件特性的影响

Influences of Drain-to-Source Distance on the Characteristics of AlGaN / GaN HEMTs

采用相同的欧姆接触,栅长为100 nm的T型栅以及50 nm的氮化硅(Si N)表面钝化等器件工艺,制备了漏源间距分别为2和3μm的AlGaN/Ga N高电子迁移率场效应晶体管(HEMT)。研究发现,当漏源间距从2μm增加至3μm后,器件的直流特性略有下降,如在Vgs为1 V下的饱和电流密度从1.4 A/mm下降至1.3 A/mm。此外,器件的射频特性也略有下降,电流增益截止频率(fT)从121 GHz降至116 GHz,最大振荡频率(fmax)从201 GHz下降至189 GHz。然而,器件的击穿特性却有显著提升,击穿电压从44 V提升至87 V。在实际器件设计制备过程中可考虑适当增加漏源间距,在保持直流和射频特性的前提下,提升器件的击穿特性。

AlGaN/GaN high electron mobility transistors （HEMTs） with different drain-to-source distances （2 μm and 3 μm） were fabricated, using the same device processing, such as the Ohmic contact, 100 nm T-shaped gate, 50 nm SiN surface passivation and so on. The results show that the DC performance of the device decrease slightly with the increasing drain-to-source distance from 2 μm to 3 μm, such as the drain current density decreases from 1.4 A/ram to 1.3 A/ram when Vgs = 1 V. Moreover, the RF characteristics of the fabricated AlGaN/GaN HEMT also decrease slightly with the increasing drain-to-source distance, such as the cut-off frequency （fT） decreases from 121 GHz to 116 GHz, and the maximum oscillation frequency （fmax） decreases from 201 GHz to 189 GHz. However, the breakdown characteristics of the device improve obviously with the increasing drain-to-source distance from 2 μm to 3 μm. The breakdown voltage increases from 44 V to 87 V. Thus, the increasing drain-to-source distance properly can be considered to increase the breakdown characteristics during the device＇ s design and fabrication, while remaining the DC and RF characteristics.