用异质结构控制GaN阴极电子发射

Electron Emission from GaN Cathode Controlled by Heterostructures

从自洽求解薛定谔方程和泊松方程出发,研究了GaN异质结构上偏压变化时异质结电场的变化。发现异质结量子阱能把外电场屏蔽在异质界面以外。利用这种异质结量子阱的屏蔽效应,可以使外电场都降落在异质结表面来控制表面势。为了把表面电势剪裁成半导体阴极所需的陡直下降的电势结构,进一步深入研究了双势垒异质结的电场结构,发现外面的异质结能屏蔽里面异质结的势垒。利用这种双势垒异质结的屏蔽效应设计出可由偏压直接控制电子亲合势的异质结构,从而为半导体阴极开辟出一条新的研究途径。

From the self-consistent solution of the Schrodinger equation and Poisson equa- tion, the electric field distributions inside the GaN heterostructures under different applied volt- age are investigated in this paper. It is found that the applied electric field can be screened outside the heterojunction interface. Taking advantage of the screening effect from heterojunction quan- tum well, the applied electric field may be dropped across the heterojunction surface to control the surface potential of semiconductor cathode. In order to tailor the surface potential to meet the demand of semiconductor cathode a new heterostructure with two coupling quantum wells is in- vestigated, from which it is found that the inner quantum well potential is screened by the outer quantum weI1. By using the screening effect of heterostructure with two coup]Ling quantum wells a new heterostructure with electron affinity controllable by applied voltage is designed, from which a new way to research semiconductor cathode is opened.