Residual dopant levels in silicon feedstock grown by pilot-scale atmospheric pressure iodine vapor transport

The atmospheric pressure iodine vapor transport method for polysilicon feedstock generation from metallurgical-grade silicon was introduced in 2002. More recent industrial pilot-scale development of the process has produced feedstock with improved electrically-active impurity control. Czochralski single crystal growth was carried out using relatively recent polysilicon produced by this method. The polysilicon was found to produce n-type single crystal material with some compensating p-type component. The resistivity data could be approximately fit to normal freezing curves with initial P and B concentrations of C_o = 1.1 × 10¹⁵ and C_o = 3.3 × 10¹⁴ atoms·cm^-3 respectively.