GaN HFET研究中的钝化、场板和异质结构设计

Passivation,Field Plate and Heterostructure Design in GaN HFETs

从AlGaN/GaN沟道阱电子状态出发,深入研究了GaNHFET研究中的钝化和场板电极。提出了用低、高Al组分比势垒制成复合势垒,来抬高势垒和增大势垒宽度,强化沟道阱的量子限制。强调了负极化电荷在强化沟道阱量子限制和能带剪裁中的重要作用。依据内沟道、外沟道和欧姆接触对势垒的不同要求设计出二维异质结构。通过特殊的异质结构设计和后工艺剪裁制成了满足肖特基势垒和欧姆接触的两种不同的异质结构。把优质Si3N4钝化膜同复合势垒结合起来塑造出满足外沟道要求的异质结构,从而实现了HFET二维异质结构的优化设计。证实了这种新沟道阱中的电子在三种不同栅压下的强二维特性,强调了背场板和背势垒在器件研究中的重要作用。

The passivation and field plate in GaN HFETs were investigated from the electron states in the channel well of GaN HFETs. A compound barrier constituted of low and high Al composition barriers was proposed to build up the high and wide barrier and strengthen the quantum confinement of the channel well. The important role of the negative polarization charge in strengthening the quantum confinement of the channel well and the energy band tailoring was emphasized. A two-dimensional heterostructure was designed according to the different requirements of inner channel, outer channel and ohmic contact barriers. Two different heterostructures satisfying the different requirements for Schottky barrier and ohmic contact were implemented through the special heterostructure design and post technology tailoring. The heterostructure satisfying the requirement for the outer channel was constructed by combining high quality passivation technology with the compound barrier, thus the optimized two-dimensional heterostructure was fabricated. The strong two-dimensional characteristics for electrons in this new channel well were demonstrated under three different gate voltages, where the important roles of the back-side field plating effect and back barrier in HFETs were emphasized.