4H-SiC同质外延层的质量表征

在高纯半绝缘4H-SiC偏8°衬底上同质外延生长了高质量的外延层,利用X射线双晶衍射、原子力显微镜(AFM)、汞探针C-V以及霍尔效应等测试方法,对样品的结晶质量、表面粗糙度、掺杂浓度以及电子迁移率进行了分析测试,证实外延层的结晶质量相对于衬底有着很大的改善。在同质外延7.5μm的外延层后,其半高宽从衬底的30.55arcsec减小到27.85arcsec;外延层表面10μm×10μm的粗糙度(RMS)为0.271nm;室温下,样品的掺杂浓度为1×1015cm-3时,霍尔迁移率高达987cm2/(V.s);浓度为1.5×1016cm-3时,霍尔迁移率为821cm2/(V.s)。77K时,霍耳迁移率分别为1.82×104cm2/(V.s)和1.29×104cm2/(V.s)。掺杂浓度的汞探针C-V测试结果与霍尔效应的实验数据一致。

Characterization of 4H-SiC Homoepitaxial layers

High quality 4H-SiC homoepitaxial layers were grown on 8° off-axis 〈0001〉 HP-S.I.4H-SiC substrates.The crystalline quality and the electrical properties of the epilayers were characterized by using double-crystal X-ray diffraction(XRD),atomic force microscopy(AFM)and hall effect,respectively.Compared with the substrates,the crystalline quality of the epilayers was improved.The FHWM of the 4H-SiC crystal is reduced from 30.55 arcsec to 27.85 arcsec after growing 4H-SiC epilayers with 7.5 μm thickness.The RMS of the sample in the area of 10 μm×10 μm is 0.271 nm.The room-temperature electron mobility is 821 cm2/(V·s) at 1.5×1016 cm-3 doping concentration and 987 cm2/(V·s) at 1×1015 cm-3 doping concentration,respectively.The hall mobility is 1.82×104 cm2/(V·s) and 1.29×104 cm2/(V·s) at 77 K,respectively.The doping concentrations measured by mercury C-V are well consisted with those measured by the hall effect.