RF-MBE生长的高Al势垒层AlGaN/GaN HEMT结构(英文)

RF-MBE Grown AlGaN/GaN HEMT Structure with High Al Content

采用RFMBE技术,在蓝宝石衬底上生长了高Al组分势垒层AlGaN/GaNHEMT结构.用三晶X射线衍射分析得到AlGaN势垒层的Al组分约为43%,异质结构晶体质量较高,界面比较光滑.变温霍尔测量显示此结构具有良好的电学性能,室温时电子迁移率和电子浓度分别高达1246cm2/(V·s)和1.429×1013cm-2,二者的乘积为1.8×1016V-1·s-1.用此材料研制的器件,直流特性得到了提高,最大漏极输出电流为1.0A/mm,非本征跨导为218mS/mm.结果表明,提高AlGaN势垒层Al的组分有助于提高AlGaN/GaNHEMT结构材料的电学性能和器件性能.

A Si doped AlGaN/GaN HEMT structure with high Al content (x=43%) in the barrier layer is grown on sapphire substrate by RF-MBE.The structural and electrical properties of the heterostructure are investigated by the triple axis X-ray diffraction and Van der Pauw-Hall measurement,respectively.The observed prominent Bragg peaks of the GaN and AlGaN and the Hall results show that the structure is of high quality with smooth interface.The high 2DEG mobility in excess of 1260cm2/(V·s) is achieved with an electron density of 1.429×10 13cm -2 at 297K,corresponding to a sheet-density-mobility product of 1.8×10 16V -1·s -1.Devices based on the structure are fabricated and characterized.Better DC characteristics,maximum drain current of 1.0A/mm and extrinsic transconductance of 218mS/mm are obtained when compared with HEMTs fabricated using structures with lower Al mole fraction in the AlGaN barrier layer.The results suggest that the high Al content in the AlGaN barrier layer is promising in improving material electrical properties and device performance.