Ⅲ族氮化物HFET中的电流崩塌和二维电子气

讨论了Ⅲ族氮化物HFET中电流崩塌和沟道内二维电子气特性间的关联,提出了描述产生电流崩塌时电子动态运动的微观模型。栅延迟电流崩塌被归因于栅-漏电极间隙中表面态与其下沟道中的电子交换。异质结极化感应的表面电荷不稳定性和沟道中二维电子气的量子限制特性是决定电流崩塌的两个重要因素。应用这一微观模型解释了实验中观察到的电流崩塌现象。通过适当的异质结构优化设计可望研制出无电流崩塌的Ⅲ族氮化物HFET。

Current collapse and two dimensional electron gas in Ⅲ-nitride HFET

The relationship between the current collapse and the two dimensional behavior of electron gas in Ⅲ-nitride HFET is discussed,from which a microscopic mechanism to describe the dynamic electron process of current collapse is proposed. The current collapse is attributed to an electron exchange process between the states of two dimensional electron gas in channel and the surface states induced by polarization. It is shown that the instability of polarization-induced surface charge and the quantum confined behavior of 2DEG states are two important factors determining current collapse behavior. Various experimental results for current collapse have been explained by this microscopic model. It is expected to eliminate the current collapse through appropriate optimized design of heterostructure.