氢氟酸刻蚀对Ni/6H-SiC接触性质的作用

Effect of hydrofluoric acid etching time on Ni/6H-SiC contacts

采用浓度为10%的氢氟酸(HF)刻蚀6H-SiC单晶片,研究了HF刻蚀时间对Ni/6H-SiC接触性质的影响.经24h刻蚀的SiC基片在溅射Ni层后,其接触表现良好线性的电流-电压(I-V)曲线.低于这个腐蚀时间的接触具有明显的势垒,但在大于1000℃快速退火后,也得到了良好线性的I-V曲线.X射线衍射(XRD)和俄歇能谱(AES)深度元素分析表明Ni2Si和C是快速退火后的主要产物.XRD和低能反射电子能量损失谱表明表层的C元素是以非晶态存在.通过研究高温快速退火下元素的互扩散及HF与SiC表层反应机理,发现SiC表面富碳层是这两种方法形成欧姆接触的关键因素.

The effect of hydrofluoric acid （HF） etching time on Ni/6H-SiC ohmic contacts was investigated. The as-deposited Ni/6H- SiC contacts prepared by 6H-SiC substrates which have been subjected to different HF etching time have different I-V characteristics. For SiC substrates etched for less than 12 hours, the contacts were rectifying, and excellent linear curves were observed after high temperature thermal annealing. X-ray diffraction, Auger electronic spectroscopy and low-energy reflection electron energy loss spectroscopy showed that Ni2 Si and amorphous C were the main reaction products after annealing. For SiC substrate etched for 24 hours, the as-deposited Ni/6H-SiC contact was ohmic. The carbon-enriched layer （CEL） on the SiC surface plays an important role in the formation of ohmic contact.