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采用金属有机化合物化学气相沉积(MOCVD)方法制备了不同Al组分(x=0.19,0.22,0.25,0.32)的Al x Ga1-x N/AlN/GaN结构的高电子迁移率晶体管(HEMT)材料。研究了Al x Ga1-x N势垒层中Al组分对HEMT材料电学性质和结构性质的影响。研究结果表明,在一定的Al组分范围内,二维电子气(2DEG)浓度和迁移率随着Al组分的升高而增大。然而,过高的Al组分导致HEMT材料表面粗糙度增大,2DEG迁移率降低,该实验现象在另一方面得到了原子力显微镜测试结果的验证。在最佳Al组分(25%)范围内,获得的HEMT材料的2DEG浓度和室温迁移率分别达到1.2×1013cm-2和1 680 cm2/(V·s),方块电阻低至310Ω/□。
A high electron mobility transistor (HEMT) material with Al x Ga 1-x N / AlN / GaN structure with different Al composition (x = 0.19, 0.22, 0.25, 0.32) was prepared by metal organic chemical vapor deposition (MOCVD) . The effect of Al composition in Al x Ga 1-x N barrier layer on the electrical and structural properties of HEMT materials was investigated. The results show that the 2DEG concentration and mobility increase with the increase of Al content within a certain range of Al composition. However, the excessively high Al content results in an increase in the surface roughness of the HEMT material and a decrease in the 2DEG mobility. This experimental result is verified by AFM test results on the other hand. The 2DEG concentration and the room temperature mobility of the obtained HEMT material reach 1.2 × 1013 cm -2 and 1 680 cm 2 / (V · s), respectively, in the range of the best Al composition (25%), and the sheet resistance is as low as 310Ω / □.