Au电极与CdMnTe晶体的表面接触电阻率研究

Investigation of the contact resistivity of Au contact on CdMnTe crystal

采用圆形传输线模型研究了金(Au)电极与碲锰镉(CdMnTe)晶体的欧姆接触特性,Au电极采用AuCl3化学镀金法制备,计算了其接触电阻率。实验探讨了表面处理和退火对Au/CdMnTe接触电阻率的影响。结果表明,CdMnTe晶体经过化学抛光和化学机械抛光后Au/CdMnTe的接触电阻率分别为544.5和89.0Ω·cm2。通过AFM与XPS分析了晶体表面的形貌与成分,发现表面粗糙度和富Te成分对CdMnTe薄层电阻和载流子传输长度有较大的影响,决定了接触电阻率的大小。在150℃空气气氛退火1h后,经CP和CMP表面处理的样品,Au/CdMnTe接触电阻率均减小,分别为313.6和30.2Ω·cm2。退火促进了Au向CdMnTe晶体的扩散,使接触电阻率进一步降低,欧姆接触性能提高。

The ohmic characteristics of Au/CdMnTe contact were investigated by circular transmission line model（CTLM）.The Au contacts on CdMnTe wafers were deposited with the electroless AuCl_3 technique.The influence of surface polishing and annealing on the contact resistivity of Au/CdMnTe were analyzed.The contact resistivity of Au/CdMnTe on the chemical polished and chemical mechanical polished surfaces were 544.5 and 89.0Ω·cm^2,respectively.The surface morphology and composition of CdMnTe wafers were characterized by AFM and XPS,which revealed that the surface roughness and Te-rich state had great effect on the sheet resistance and the carrier transmission length,thus determined the contact resistivity of Au/CdMnTe.After annealing at 150 efor 1h,the contact resistivity of the Au/CdMnTe contact treated by CP and CMP both decreased to 313.6 and 30.2Ω·cm^2.The annealing procedure enhanced the diffusion of Au into the CdMnTe crystal,which further decreased the contact resistivity,and the quality of the ohmic contact was improved.