气态源分子束外延AlxGa1-xAs(x=0～1)材料中Si的掺杂行为研究

研究了Si在AlxGa1-xAs(0≤x≤1)中的掺杂行为.为比较Al組份对Si掺杂浓度的影响,在用气态源分子束外延生长(GSMBE)掺Si n型AlxGa1-xAs(0≤x≤1)的所有样品时,n型掺杂剂Si炉的温度恒定不变.用Hall效应测量外延层的自由载流子浓度和迁移率,用X射线双晶衍射迴摆曲线测量外延层的组份.测试结果表明,当AlxGa1-xAs中Al组份从0增至0.38时,Si的掺杂浓度从4×1018cm-3降至7.8×1016cm-3,电子迁移率从1900 cm2/Vs降至100 cm2/Vs.这与AlxGa1-xAs材料的Γ-X直接—间接带隙的转换点十分吻合.在AlxGa1-xAs全组份范囲内,自由载流子浓度隨Al组份从0至1呈“V”形变化,在X=0.38处呈最低点.在x>0.4之后,AlxGa1-xAs的电子迁移随Al组分的增加,一直维持较低值且波动幅度很小.

BEHAVIOR OF Si INCORPORATION IN AlxGa1-xAs (x=0 TO 1) GROWN BY GAS SOURCE MOLECULAR BEAM EPITAXY

The doping behavior of Si in AlGaAs with AlAs mole fraction from 0 to 1 was reported. Si-doped AlxGa1-xAs layers were grown by gas source molecular beam epitaxy with a constant Si cell temperature for all samples. The electrical properties and composition of the ternary alloys were characterized by Hall effect and X-ray diffraction,respectively. Results show that the electron concentration of Si-doped AlxGa1-xAs varying with Al mole fraction has a minimum value at x=0.38,which is the Γ-X direct-indirect band crossover of AlGaAs system. The Hall mobility decreases with the increasing of AlAs mole fraction till about x=0.4,hereafter it remains at a low value of mobility with small change rate.