由缺陷引起的Burstein-Moss和带隙收缩效应对CdIn2O4透明导电薄膜光带隙的影响

在Ar+O2气氛，采用射频反应溅射Cd In靶制备CdIn2O4（CIO）薄膜.通过对不同衬底 温度下制备和沉积后在氩气流中退火的薄膜进行透射、反射和Hall效应的测量和分析发现， 随着衬底温度的降低，载流子浓度呈上升趋势，而吸收边呈现先是“蓝移”然后“红移”的 现象.从理论上阐述了高浓度的点缺陷对CIO氧化物薄膜的能带产生的重要影响，这些影响主 要体现在带尾的形成，Burstein Moss(B M)漂移和带隙收缩.另外，衬底温度的变化将对 薄膜的迁移率有重要影响.对于CIO薄膜，由缺陷产生的空穴浓度将对薄膜的带隙收缩产生重 要影响并将直接影响到薄膜的光透性.由于存在吸收带尾，利用传统的“外推法”获得薄膜 的光带隙并不适合简并半导体，而应使用更为准确的“拟合法”. 关键词： 射频反应溅射 CdIn2O4透明导电薄膜 Burstein Moss漂移 带隙收缩 电学性 质 光学性质

Effect on optical band-gap of transparent and conductive CdIn2O4 thin film due to defects-induced burstein-moss and band-gap narrowing characteristics

Transparent and conductive oxides CdIn 2O 4 (CIO) thin films were prepared by RF reactive sputtering from a Cd-In alloy target in Ar O 2 atmosphere. By the analysis and measurements of transmittance spectra and Hall_effect of different samples prepared at different substrate temperatures and post_deposition anneali ng in an Ar gas flow, it was found that the carrier density increases with the decrease of substrate temperature, but the absorption edge shows an abrupt change from a blu e_shift to a red_shift. Theoretically, the paper formulated the effect on band s tructur e due to higher density of point defects, it embodies the band_tailing, Burstein _Moss (B_M) shift and band_gap narrowing. In addition,density of ionized impurity substrate temperature induced will affec t the carrier mobility.The hole density impurity_induced will infl uences the magnitude of optical band_gap and transmittance of light. Since extra polation method does not fit degenerate materials, a more accurate method of obt aining band_gap is the method of curve fitting.