摘要
采用自行设计的水平冷壁低压化学气相沉积(LPCVD)方法在偏向〈1120〉晶向8°的n型4H SiC(0001)衬底上进行了同质外延生长.在5 3×103Pa的低压下,外延膜生长速率超过3μm/h.电容电压法测试表明在非有意掺杂外延膜中净施主浓度为8 4×1016 cm-3.Nomarski显微镜观察表明厚外延膜的表面光滑,生长缺陷密度很低.AFM测试显示表面均方根粗糙度为0 3nm,没有观察到宏观台阶结构.Raman谱线清晰锐利,表现出典型的4H SiC特征.在低温PL谱中,近带边区域出现很强的自由激子峰,表明样品是高质量的.
High quality and thick 4H-SiC(0001) epilayer has been grown on 8° off-axis 4H-SiC(0001) substrate by a horizontal cold-wall chemical vapor deposition system,which was designed and built at the author’s group.The growth rate is over 3μm/h at a low pressure of 5.3×103Pa.A low net donor concentration of 8.4×10 16 cm -3 is obtained in the unintentionally doped epilayer by C-V curve.A specular surface is observed by Nomarski microscopy,indicating low density of growth defects and AFM shows a low RMS of 0.3nm without macrosteps.The sharp Raman lines show typical features of 4H-SiC.In low temperature photoluminescence,very strong free exciton peaks are observed,indicating the high purity and quality of the epilayer.
