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肖特基金属影响AlGaN/GaN异质结材料的电学特性。在AlGaN/GaN异质结材料上分别制备得到铱/金(Ir/Au)、镍/金(Ni/Au)和铼/金(Re/Au)三种不同肖特基接触的二极管器件,基于电流电压(I-V)和电容电压(C-V)测试结果,计算得到了三者的沟道二维电子气(2DEG)密度。并通过薛定谔和泊松方程自洽求解计算得到了三者的肖特基接触势垒高度、导带底能带图和沟道2DEG分布情况。研究发现金属功函数越小,势垒高度反而越高,沟道2DEG密度越小,GaN侧的沟道三角形势阱变得越浅。这主要是由于金属功函数越小,电子能量越高,与AlGaN势垒层表面态的电子耦合作用越强所致。
Schottky metal affects the electrical properties of AlGaN / GaN heterojunction materials. Three kinds of diode devices with different Schottky contacts such as iridium / gold (Ir / Au), nickel / gold (Ni / Au) and rhenium / gold (Re / Au) were fabricated on AlGaN / GaN heterojunction materials respectively. Current voltage (IV) and capacitance voltage (CV) test results, calculated three channel 2D electron gas (2DEG) density. The Schottky barrier height, the band diagram at the bottom of the conduction band and the 2DEG distribution of the channel were calculated by self-consistent solutions of Schrödinger equation and Poisson equation. It is found that the smaller the metal work function, the higher the barrier height is, the smaller the channel 2DEG density is, and the shallower the channel triangular well on the GaN side becomes. This is mainly because the smaller the metal work function, the higher the electron energy, and the stronger the electron coupling with the surface state of the AlGaN barrier layer.