采用物理气相传输(PVT)法,通过改变石墨坩埚顶部结构,实现了低氮和硼碳化硅单晶生长的目标.对抛光后的4H-SiC晶片进行二次离子质谱(SIMS)测试,B和N的浓度相应降低1个和2个数量级.采用非接触电阻率测试仪测试晶圆的电阻率均大于4×109Ω·cm;红外透射谱测试结果表明,波数2500~4200 cm-1超过78%的透过率.显微拉曼光谱测试晶圆的4H-SiC晶型面积为100%.结果表明,该方法不仅降低晶体中的B和N等杂质浓度,并成功地制备出直径100 mm的高纯半绝缘4H-SiC单晶.%By using the physical vapor transport (PVT) method, the growth of low nitrogen and boron silicon carbide single crystals was achieved by changing the structure of the top of the graphite crucible. The secondary ion mass spectrometry(SIMS) test of polished 4H-SiC wafers showed that the concentration of B and N decreased 1 and 2 orders of magnitude; and non contact resistivity test indicated that the resistivity of wafers were greater than 4×109?·cm; Infrared transmission spectra showed that the transmittance is about more than 80% in the range of 2500~4200 cm-1; Micro Raman spectroscopy test showed that the crystal polytype of the 4H-SiC substrate was 100%. The results show that this method can not only reduce the impurity concentration of B and N in the crystal but also successfully prepare the high purity semi-insulating 4H-SiC single crystal with a diameter of 100 mm.
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