背势垒层结构对AlGaN/GaN双异质结载流子分布特性的影响

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 关键词： AlGaN/GaN 双异质结构 限域性 寄生沟道

The effect of back-barrier layer on the carrier distribution in the AlGaN/GaN double-heterostructure

The one-dimensional self-consistent simulation of the band diagram and carrier distribution of the AlGaN/GaN double hetero-structure is firstly carried out to research the effect of the thickness and Al content of the AlGaN back-barrier layer on the carrier distribution. Then the AlGaN/GaN double hetero-structure materials with different back-barrier layers were grown by low-pressure MOCVD method on c-plane sapphire substrate. The mercury probe CV measurement was carried out to verify the results of theoretical simulation. The results of theoretical simulation and experiment both indicate that with the increase of Al content and thickness of the AlGaN back-barrier layer, the two-dimensional electron Gas density becomes low in the main channel and high in the parasitic channel gradually.The increase of Al content and thickness of the AlGaN back-barrier layer effectively enhances the two-dimensional electron Gas confinement but simultaneity produces higher-density parasitic channel. So a compromise has to be made between the improvement of the two-dimensional electron Gas confinement and the restraint of the carrier density in parasitic channel in designing the double heterostructure.