单源共蒸法制备CuInS_2薄膜及特性分析

Preparation and properties of CuInS_2 thin film deposited by single-source vacuum co-evaporation

将单质Cu、In和S粉末按一定比例均匀混合,单源共蒸发沉积CuInS2薄膜。氮气保护对薄膜进行热处理。研究不同热处理条件对薄膜表面形貌、化学组分及电学特性的影响。XRD分析给出直接沉积的CuInS2薄膜为黄铜矿结构,整体性能较差。经400℃、20 min热处理后,CuInS2薄膜特性得到明显的改善,导电类型呈P型,体内元素化学计量比Cu:In:S=1:0.9:1.5接近标准值,Cu含量略多,电阻率为4.8×10-2Ω.cm,薄膜的直接光学带隙1.42 eV,光吸收系数105cm-1。440℃、10 min热处理的薄膜,晶相结构没变但导电类型转为N型,元素化学计量比Cu:In:S=1:2.3:0.8,In元素过量,电阻率为1.3×10-2Ω.cm,光吸收系数104cm-1,直接光学带隙1.39 eV。

By making the pure Cu, In, and S powder mixed evenly in proportion, CuInS2 thin films were prepared utilizing the single source co-evaporation method, followed by heat-treatment in N2. The effects of different heat-treatment conditions on the film surface morphology, chemical composition and electrical properties were investigated. XRD analysis show that the as-deposited films present deficiency in crystallization with chalcopyrite structure. After heat-treatment for 20min at 400%, the film properties have been improved with P-type conductivity. The stoichiometric ratio of Cu：In：S in the film is 1：0.9：1.5, which is close to the standard stoichiometry though the amount of Cu is slightly more. The resistivity, optical bandgap and absorption coefficient of the film is 4.8×10-2Ω·cm, 1.42eV and 10^5cm-1, respectively. The crystalline structure of the film doesn＇t change after heat-treatment for 10min at 440%, but the conduction type converts to N-type. The ratio among Cu,In and S elements is 1：2.3：0.8, showing that In is excess. The resistivity, absorption coefficient and bandgap of this sample are 1.3×10-2Ω·cm, 10^4cm-1 and 1.39eV, respectively.