摘要
研究了垂直梯度凝固法(VGF法)生长的掺Si低阻GaAs单晶材料的晶格缺陷和性质,并将VGF法和LEC法生长的非掺半绝缘GaAs单晶进行了比较.利用A-B腐蚀显微方法比较了两种材料中的微沉积缺陷,对其形成原因进行了分析.利用荧光光谱研究了掺Si-GaAs单晶中Si原子和B原子的占位情况和复合体缺陷.Hall测量结果表明,掺Si低阻VGF-GaAs单晶中存在很强的Si自补偿效应,造成掺杂效率降低.VGF-GaAs单晶生长过程中高的Si掺杂浓度造成晶体中产生大量杂质沉积,而杂质B的存在加重了这种现象.对降低缺陷密度,提高掺杂效率的途径进行了分析.
Micro-defects and properties of Si-doped,low resistivity GaAs single crystal grown by the vertical gradient freeze （VGF） method are studied and compared with undoped semi-insulating GaAs grown by VGF and liquid encapsulated Czochralski-grown （LEC） methods. Using the A-B etching microscopy method, micro-precipitated defects in the two materials are compared and their formation mechanism is analyzed. Lattice occupation of Si and B atoms and their complex defects are investigated by photoluminescence spectroscopy. Hall measurement results indicate that there is a strong Si self-compensation in the low resistive Si-doped VGF- GaAs single crystal, resulting in a reduction of n-type doping efficiency. As a result, a high initial doping concentration of Si is used in the process of VGF growth of n-type GaAs,and a large amount of impurity precipitate is formed. This situation is enhanced when a high concentration of B in the VGF grown GaAs exists. An approach to reduce defects and increase doping efficiency is discussed.
