三维a-IGZO薄膜中的电子—电子散射  

Electron-electron scattering in three-dimensional amorphous IGZO films

作　　者：张辉[1] 杨洋[1] 李志青[1] 

机构地区：[1]天津大学理学院天津市低维功能材料物理与制备技术重点实验室,天津300350

出　　处：《物理学报》2016年第16期205-210,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11174216);高等学校博士学科点专项科研基金(批准号:20120032110065)资助的课题~~

摘　　要：本文利用射频磁控溅射法制备了一系列厚度约800 nm的非晶铟镓锌氧化物(a-IGZO)薄膜,并对其电输运性质和低温的电子退相干机理进行了系统的研究.研究发现,所有a-IGZO薄膜中,载流子浓度均不随温度变化,高温区的电阻-温度系数为正,说明样品具有类金属导电特性.通过对薄膜低温磁电阻的测量,获得了电子退相干散射率与温度的关系.分析表明,薄膜中电子-声子散射率远小于小能量转移电子-电子散射率,小能量转移电子-电子散射率主导电子退相干散射率与温度的依赖关系.Electron dephasing process is important and interesting in disordered conductors. In general three-dimensional （3D） disordered metals, the electron-electron （e-e） scattering is negligibly weak compared with the electron-phonon （e-ph） scattering. Thus, the theoretical prediction concerning the e-e scattering rate 1/τee as a function of temperature T in 3D disordered conductor has not been fully tested so far, though it was proposed four decades ago. In the frame of free-electron-like model, the e-ph relaxation rate 1/τep is proportional to carrier concentration n, while the small- and large-energy-transfer e-e scattering rate obey the laws 1/τSee ∝ n-4/3 and 1/τLee ∝ n-2/3, respectively. In other words, e-e scattering may dominate the dephasing processes in 3D disordered metals with su？cient low carrier concentrations. In the present work, we systematically investigate the electronic transport properties of amorphous indium gallium zinc oxide （a-IGZO） prepared by the radio frequency sputtering method. The carrier concentrations of the highly degenerate IGZO films are all ～5 ＆#215; 1019 cm？3, which are 3–4 orders of magnitude lower than those of typical metals. Our thick films （～800 nm） are 3D systems with respect to weak-localization （WL） effect and e-e scattering. X-ray diffraction patterns of the films indicate that our films are all amorphous. For each film, the resistivity increases with the increase of the temperature in the high temperature region （T ＆gt;200 K） and the carrier concentration is almost invariable in the whole measured temperature range. This indicates that the films possess metal-like transport properties. By comparing the low-field magnetoconductivity versus magnetic field data σ（B） with that from the 3D WL theory, we extract the electron dephasing rate 1/τФ at different temperatures in the low temperature region. It is found that 1/τФaries linearly with T 3/2 for each film. The T 3/2 behavior of 1/τФ can be quantitatively described

关 键 词：电子散射 弱局域效应 电子输运性质 

分 类 号：O484[理学—固体物理]