GaN HFET中的实时能带和电流崩塌(续)

Real Time Bands and Current Collapse in GaN HFET

从场效应管能带和能带峰耗尽的新概念出发,提出了研究GaN HFET射频工作中实时能带的新课题。运用自洽求解二维泊松方程和薛定谔方程的能带计算软件详细计算了不同栅压和漏压下的实时稳态能带,由此求出各种实时能带下的局域电子气密度和局域电子气势垒。考虑从应力偏置转换到测试偏置时异质结充放电引起的非稳态能带变化,用电子状态转换及其在异质结充放电中的输运行为成功解释了各类DLTS和电流崩塌实验中的动态行为。建立起新的电流崩塌能带模型。详细比较了陷阱模型和能带模型对电流崩塌和器件射频工作的不同描述。从电流崩塌同异质结构关联研究中提出新的器件优化设计方案。

Proceeding from new ideas of bands of field-effect transistor and exhaustion of peak energy band,a new study of real time bands of GaN HFET during radio frequency operation is proposed.Through the self-consistent solution of two dimensional Poisson equation and Schr?dinger equation,the real time stable state bands under different drain and gate voltages are calculated by the new bands calculation soft-ware,from which the densities of localized electron gas and the localized electron gas potentials are obtained.Considering the evolution of unstable state bands caused by heterojunction charging and discharging from stress bias to test bias,various dynamic behaviors in DLTS measurements and current collapse experiments have been explained successfully by the electron states transform and their transport behavior during the charging and discharging processes of heterojunction.A new band model of current collapse has then established.The different explanations for various current collapse behaviors and radio frequency operations in traps model and band model are compared in detail.At last a new way to optimize GaN HFET design has been proposed through the study of correlation between current collapse and hetero-structure.