含有Al组分阶变AlGaN过渡层的Si基AlGaN/GaN HEMT

采用一个AlN缓冲层和两个Al组分阶变的AlGaN过渡层作为中间层,在76.2mm Si衬底上外延生长出1.7μm厚无裂纹AlGaN/GaN异质结材料,利用原子力显微镜、X射线衍射、Hall效应测量和CV测量等手段对材料的结构特性和电学性能进行了表征。材料表面平整光滑,晶体质量和电学性能良好,2DEG面密度为1.12×1013cm-2,迁移率为1 208cm2/(V.s)。由该材料研制的栅长为1μm的AlGaN/GaN HEMT器件,电流增益截止频率fT达到10.4GHz,这些结果表明组分阶变AlGaN过渡层技术可用于实现高性能Si基GaN HEMT。

AlGaN/GaN HEMT on Si Substrate with Al-content Step-graded AlGaN Transition Layers

A 1.7 μm thick,crack-free AlGaN/GaN heterostructure had been grown on 76.2 mm diameter Si substrate by using an AlN buffer layer and two Al-content step-graded AlGaN transition layers(TL).The structural and electrical properties of the AlGaN/GaN heterostructure were characterized by atomic force microscopy,X-ray diffractometer,Hall and capacitance-voltage measuring instruments.The AlGaN/GaN heterostructure containing the step-graded AlGaN TL exhibited flat surface morphology and good crystalline quality.An electron mobility of 1 208 cm2/(V·s) with sheet carrier density of 1.12×1013 cm-2 was measured on the heterostructure.High electron mobility transistors(HEMTs) with 1 μm gate lengths were fabricated by this heterostructure.A current gain cutoff frequencies(fT) of 10.4 GHz was obtained on the AlGaN/GaN HEMTs.These results show that Al-content step-graded AlGaN transition layers could be used to achieve GaN HEMTs on Si substrate with high performance.