改进的水平梯度凝固法生长无位错掺硅的砷化镓单晶

本文提出具有准双抛物线温度分布的水平梯度凝固法生长GaAs晶体.利用此法成功地生长了取向〈111〉B和〈211〉B的掺Si无位错GaAs单晶.晶体在生长过程中,生长界面微凸,与生长方向近乎垂直,表明生长区热对称性良好,从而避免了沿用的水平Bridgman法的一些弊端.文中对该法的其它一些工艺特点也作了详尽的论述.此外,认为掺Si降低位错密度的作用,可能与形成的Si_GaV_Ga络合物与位错的交互作用有关.

A MODIFIED HORIZONTAL GRADIENT-FREEZE APPROACH TO THE GROWTH OF DISLOCATION-FREE Si-DOPED GaAs SINGLE CRYSTALS

A modified horizontal gradient-freeze approach with quasidouble parabolic temperature profile has been developed for growing GaAs single cryatals. Using this approach, the dislocation-free Si-doped crystals with <111>B and <211> B oriented seeds have been grown successfully. It has been found that the solid-liquid interface is slightly convex and nearly perpendicular to the growth direction during the growth process, indicating good thermal symmetry in the growth region, and so some deficiencies due to the inclined and slightly concave interface in conventional horizontal Bridgman growth could be avoided. Some other features in this approach are also discussed. It is suggested that the effectiveness of dopant Si for reducing the dislocation density of the crystals may be related to the interaction between Si_GaV_Ga complexes and dislocations.