Study On Si_1-XGe_X Single Crystal Growth And Its Performance

SiGe alloy crystal is of variable band gap and parameters according to the composition, and is also called the secondary generation silicon material. SiGe alloy crystal has very interesting applications for micro-electronic and opto-electronic devices and thermo electric generators.Because of the particular predominance and application of SiGe crystal, the main developed countries strengthen the study of SiGe crystal. Many techniques are used to grow SiGe single crystals: Czochralski (CZ), float zone (FZ) and vertical Bridgman (VB). The CZ method is the most convenient technique for growing single crystals of large diameter. The growth of SiGe single crystal is very difficult, due to the segregation of the second component during growth. Domestic research of the growth, performance and application of SiGe single crystal is seldom.In Chapter one of this thesis, we introduced SiGe single crystal characteristics and applications for solar cell, x-raymonochromators,γlens and substrate for quantum wells. The growth methods and development were also described. In Chapter two, we introduced our study on SiGe single crystal growth. According to the request of deferent kind of device, we mainly prepared two kinds of SiGe single crystal, one kind of crystal with large diameter, free dislocation and low Ge content can be used for radiation hardened devices and solar cells. The other kind of crystal with small diameter, high Ge content and dislocations can be used for x-ray monochromators,γlens,substrate for opto-electronic devices and quantum wells. The crystal with diameter of 100mm, Ge content up to 1.1wt%, free dislocation were grown by CZ method using Si crystal puller (TDR-62) with 10 inch close heater system, and the crystal with diameter of 50 to 60mm, Ge content up to 12.92wt% were also grown by the puller using 150mm heater system. In Chapter three, we introduced the test techniques ,results and analyse of resistivity,lifetime,Ge content ,oxygen content ,dislocation density and growing interface of the SiGe single crystal we prepared.