利用温度无关点计算AlGaN／GaN肖特基势垒高度

Evaluating AlGaN /GaN Heterostructure Schottky Barrier Height by Temperature-Independence Point

基于AlGaN/GaN异质结场效应晶体管(HFET)中肖特基势垒高度的有效提取对提升器件的性能和稳定性有着重要指导意义,制备了AlGaN/GaN异质结肖特基二极管,并利用光电流谱测试得到了该样品的势垒高度。此外,测试得到该样品的正向变温电流电压(I-V)曲线,发现在正向变温I-V曲线中存在一个温度无关点,低于该点时同一偏压下电流随温度的升高而增大,高于该点时同一偏压下电流随温度的升高而减小。利用温度无关点对应的电压,结合薛定谔泊松方程自洽循环迭代,计算得到AlGaN/GaN肖特基二极管的势垒高度,发现该结果与光电流谱测试的结果非常一致,从而得到一种计算AlGaN/GaN异质结肖特基二极管势垒高度的新方法。

Extraction of Schottky barrier height for the A1GaN/GaN heterostucture field-effect transistor （HFET） is essential to improve the performance and reliability of the device. A1GaN/GaN heterostructure diode was fabricated, and the height of the Schottky barrier was measured by the photoemission measurement. Based on the measured current-voltage （I-V） curves of AIGaN/GaN Schottky diode under different temperatures, it＇s found that there is a temperature-independence point in the forward I-V curves. Below this point, the current increases with the rise of the temperature at the same voltage, while it decreases above this point. With the voltage related to the temperature- independence point, the Schottky barrier height of AlGaN/GaN diode is evaluated by self-consistently solving Schrodinger＇s and Poisson＇s equations. And the calculated result is consistent with the one obtained by the photoemission measurement. Thus, a new way of calculation of AlGaN/GaN Schottky barrier height with temperature-independence point is obtained.