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采用高压垂直温度梯度凝固法(VGF)生长了非掺、掺硫和掺铁的4 inch直径(100)InP单晶,获得的单晶的平均位错密度均小于5000 cm~(-2)。对4 inch InP晶片上进行多点X-射线双晶衍射测试,其(004)X-射线双晶衍射峰的半峰宽约为30弧秒且分布均匀。与液封直拉法(LEC)相比,VGF-InP单晶生长过程的温度梯度很低,导致其孪晶出现的几率显著增加。然而大量晶体生长结果表明VGF-InP晶锭上出现孪晶后,通常晶体的生长方向仍为(100)方向,这确保从生长的4 inch VGF-InP(100)晶锭上仍能获得相当数量的2~4 inch(100)晶片。由于铁在InP中的分凝系数很小,掺Fe-InP单晶VGF生长过程中容易出现组份过冷,导致多晶生长。通过控制生长温度梯度及掺铁量,可获得较高的掺铁InP单晶成晶率。对VGF-InP单晶的电学性质、位错密度及位错的分布特点、晶体完整性等进行了研究。
The 4 inch diameter (100) InP single crystals doped with sulfur and iron were grown by high pressure vertical temperature gradient solidification (VGF). The average single crystal dislocation densities were less than 5000 cm -2. The multi-spot X-ray double crystal diffraction test on a 4 inch InP wafer shows a half-width of about 30 arc seconds and a uniform distribution of the (004) X-ray double crystal diffraction peak. Compared with LEC, the temperature gradient of VGF-InP single crystal growth process is very low, resulting in a significant increase in the occurrence of twinning. However, a large number of crystal growth results indicate that twins are present on the VGF-InP ingot, and the crystal growth direction is usually still in the (100) direction, which ensures that a considerable amount of crystal growth is still obtained from the 4 inch VGF-InP Of 2 to 4 inch (100) wafers. Due to the small segregation coefficient of iron in InP, the composition is prone to overcooling during the growth of Fe-InP single crystal VGF, resulting in polycrystalline growth. By controlling the growth temperature gradient and the amount of iron doping, a higher InP yield can be obtained. The electrical properties of VGF-InP single crystal, dislocation density and dislocation distribution, crystal integrity were studied.