AlGaN/GaN HFET中的陷阱

Trapping in AlGaN/GaN HFET

提出了二维表面态和表面缺陷层构成的AlGaN/GaN HFET中的陷阱模型。自洽求解薛定谔方程和泊松方程得到异质结能带和沟道阱基态、激发态及二维表面态的波函数。发现表面高密度缺陷减薄了势垒层厚度,显著增强了热电子隧穿过程。从缺陷态发射电子和热电子隧穿构成的新陷阱模型出发,解释了HFET的瞬态电流、肖特基势垒的伏安特性和产生-复合噪声。最后讨论了改进材料生长和器件工艺来抑制陷阱效应,改善器件性能的途径。

A new trapping model in A1GaN/GaN HFET composed of two dimensional surface states and surface defects is proposed. From the self consistent solution of Poisson and Schr6dinger equation, the band structure, the wave functions for fundamental states, excited states, and two dimensional surface states are computed. It is found that the barrier width is thinned by the surface defects with high density to enhance the hot electron tunneling. From the electron emission of surface defects and the hot electron tunneling the transient current in HFET, the I-V characteristic in GaN Schottky diode and the generation-recombination noise behaviors are explained. At last, the new way of material growth and devices fabrication to reduce the trapping effect is discussed.