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首先通过一维自洽求解薛定谔/泊松方程,研究了AlGaN/GaN双异质结构中AlGaN背势垒层Al组分和厚度对载流子分布特性的影响.其次利用低压MOCVD方法在蓝宝石衬底上生长出具有不同背势垒层的AlGaN/GaN双异质结构材料,通过汞探针CV测试验证了理论计算的正确性.理论计算和实验结果均表明,随着背势垒层Al组分的提高和厚度的增加,主沟道中的二维电子气面密度逐渐减小,寄生沟道的二维电子气密度逐渐增加;背势垒层Al组分的提高和厚度的增加能有效的增强主沟道的二维电子气限域性,但是却带来了较高的寄生沟道载流子密度,因此,在AlGaN/GaN双异质结构的设计时,需要在主沟道二维电子气限域性的提高和寄生沟道载流子密度抑制之间进行折中考虑.
Firstly, the influence of Al composition and thickness on AlGaN backbones AlGaN backbones AlGaN / GaN heterostructure AlGaN / GaN heterostructures were studied by self-consistent one-dimensional Schrödinger / Poisson equation. Secondly, AlGaN / GaN double heterostructure materials with different back barrier layers were grown on the bottom, and the correctness of theoretical calculation was verified by the mercury probe CV test.The theoretical calculation and experimental results show that with the Al And the increase of thickness, the two-dimensional electron gas density in the main channel gradually decreases and the two-dimensional electron gas density in the parasitic channel gradually increases. The increase of the Al component and thickness in the back barrier layer can be effective Therefore, in the design of AlGaN / GaN double-heterostructure, it is necessary to design a two-dimensional electron gas in the main channel A compromise is considered between the enhancement of electron gas confinement and the suppression of the parasitic channel carrier density.