高电子迁移率晶格匹配InAlN/GaN材料研究

High electron mobility lattice-matched InAlN/GaN materials

文章基于蓝宝石衬底采用脉冲金属有机物化学气相淀积(MOCVD)法生长的高迁移率InAlN/GaN材料,其霍尔迁移率在室温和77K下分别达到949和2032cm2/Vs,材料中形成了二维电子气(2DEG).进一步引入1.2nm的AlN界面插入层形成InAlN/AlN/GaN结构,则霍尔迁移率在室温和77K下分别上升到1437和5308cm2/Vs.分析样品的X射线衍射、原子力显微镜测试结果以及脉冲MOCVD生长方法的特点,发现InAlN/GaN材料的结晶质量较高,与GaN晶格匹配的InAlN材料具有平滑的表面和界面.InAlN/GaN和InAlN/AlN/GaN材料形成高迁移率特性的主要原因归结为形成了密度相对较低(1.6×1013—1.8×1013cm-2)的2DEG,高质量的InAlN晶体降低了组分不均匀分布引起的合金无序散射,以及2DEG所在界面的粗糙度较小,削弱了界面粗糙度散射.

InAlN can be in-plane lattice matched （LM） to GaN,and the formed InAlN/GaN heterostructure is one kind of materials with high conductivity to be used in GaN-based high electron mobility transistors （HEMTs）.It is reported that the high-mobility InAlN/GaN material is grown by using pulsed metal organic chemical vapor deposition （PMOCVD） on sapphire,and the Hall electron mobility reaches 949 and 2032 cm2/Vs at room temperature and 77 K,respectively.The two-dimensional electron gas （2DEG） is formed in the sample.When 1.2 nm thick AlN space layer is inserted to form InAlN/AlN/GaN structure,the Hall electron mobility increases to 1437 and 5308 cm2/Vs at room temperature and 77 K,respectively.It is shown by analyzing the results of X-ray diffraction and atomic force microscopy and the features of PMOCVD that the crystal quality of InAlN/GaN material is quite high,and the InAlN layer LM to GaN has smooth surface and interface.The high mobility characteristics of InAlN/GaN and InAlN/AlN/GaN materials are ascribed to the fact that the 2DEG has a comparatively low sheet density （1.6×1013—1.8×1013 cm-2）,the alloy disorder scattering is weakened in the high-quality InAlN crystal since its compositions are evenly distributed,and the interface roughness scattering is alleviated at the smooth interface where the 2DEG is located.