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对垂直梯度凝固法(VGF)和液封直拉法(LCE)生长的InP单晶片进行了研究,并作了全面质量比较。用来表征缺陷结构的方法有:1)腐蚀法揭示位错。2)透射X射线形貌术(TXRT)。3)透射阴极荧光(TCL)。经腐蚀处理后,发现VGF衬底从边缘到中心观察不到滑移,EPD低(<100/cm~2)而且均匀。其低的缺陷密度与在2×10~(17)～3×10~(1(?))/cm~3范围内S的掺杂浓度无关,而是因为生长过程中降低了径向和轴向温度梯度。与此相反,掺Sn和掺Fe的LEC材料中EPD全都超过10~4/cm~2水平。对于重掺S的LEC材料(>4×10~(18)/cm~3),在片子的周界处有相当多的滑移和位错。VGF材料的TXRT研究表明,它有大面积的无位错区(≥10cm~2)。相反,LEC材料甚至在低EPD区也有位错团。TXRT和TCL能揭示由于掺杂剂不均匀地进、晶体而产生的生长条纹。在LEC材料中,生长条纹有强烈的凹曲面,这表明生长界面不是平坦的,而且由于掺杂剂进入晶体有很大的波动,因此生长条纹有明显的对比度。发现VGF生长条纹是平坦的且其对比度很弱。
InP single crystal grown by vertical gradient solidification (VGF) and liquid drop Czochralski (LCE) has been studied and compared in a comprehensive way. The methods used to characterize the defect structure are: 1) The etching method reveals dislocations. 2) Transmission X-ray topography (TXRT). 3) Transmission Cathode Fluorescence (TCL). After corrosion treatment, it was found that the VGF substrate showed no slippage from the edge to the center, and the EPD was low (<100 / cm ~ 2) and uniform. Its low defect density has nothing to do with the doping concentration of S in the range of 2 × 10 ~ (17) ~ 3 × 10 ~ (1) / cm ~ 3, but because of the reduced radial and axial To the temperature gradient. In contrast, all EPDs in the Sn-doped and Fe-doped LECs exceeded the 10-4 / cm2 level. For heavily S doped LEC materials (> 4 × 10 ~ (18) / cm ~ 3), there is considerable slippage and dislocation at the perimeter of the film. The TXRT study of VGF shows that it has a large area of no dislocation (≥10cm ~ 2). In contrast, LEC materials have dislocation clusters even in low EPD regions. TXRT and TCL can reveal growth stripes due to inhomogeneous in and out of dopants. In the LEC material, the growth stripes have a strongly concave curve, which indicates that the growth interface is not flat and there is a significant contrast between the growth stripes due to the large fluctuations of the dopants into the crystal. VGF growth stripes were found to be flat and their contrast was weak.