对4H-SiC雪崩光电探测器的Ti/Al/Au p型欧姆接触进行了详细的研究。通过线性传输线模型(LTLM)测得经930℃退火后欧姆接触的最小比接触电阻为5.4×10~(-4)Ωcm~2。分别用扫描电子显微镜(SEM)、俄歇电子能谱(AES)、X射线光电子能谱(XPS)和X射线衍射谱(XRD)对退火前后的表面形貌、金属之间以及金-半接触界面之间相互反应及扩散情况进行测试与分析,发现了影响欧姆接触性能的主要原冈。对采用此欧姆接触制备的4H-SiC雪崩光电探测器进行测试,发现器件的击穿电压约为-55 V,此时其p型电极处的电压降仅为0.82 mV,可以满足4H-SiC雪崩光电探测器在高压下工作的需要。 The Ti / Al / Au p-type ohmic contact of 4H-SiC avalanche photodetector has been studied in detail. The minimum specific resistance of ohmic contact after annealing at 930 ℃ was 5.4 × 10 ~ (-4) Ωcm ~ 2 as measured by the linear transmission line model (LTLM). The surface morphology before and after annealing, the intermetallic and the semi-contact of gold-semi-contact were studied by scanning electron microscopy (SEM), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) Interface interaction and diffusion between the test and analysis, found that the impact of ohmic contact performance of the original source. The 4H-SiC avalanche photodetector fabricated by this ohmic contact was tested and the breakdown voltage of the device was found to be about -55 V, at which time the voltage drop at the p-type electrode was only 0.82 mV, which could meet the 4H-SiC avalanche Photodetectors need to work under high pressure.