Surface Origin of High Conductivities in Undoped In2O3 Thin Films
Surface Origin of High Conductivities in Undoped In2O3 Thin Films
复制标题
DOI：
10.1103/physrevlett.108.016802
复制
发表时间：
2012-01-05
影响因子：
8.6
通讯作者：
Zunger, A.
中科院分区：
文献类型：
--
作者：
Lany, S.;Zakutayev, A.;Zunger, A.
透明导电氧化物（如ZnO、In2O3和SnO2）导电性的微观原因通常被认为是本体中的点缺陷机制，涉及内在晶格缺陷、外在掺杂或无意杂质（如氢）。我们在此证实，o空位的缺陷理论可以定量地解释在高温平衡条件下在大块In2O3样品中观察到的相当中等的电导率和非化学计量。然而，在相同的条件下（温度和O-2分压），名义上未掺杂的In2O3薄膜可以表现出惊人的高电导率，超过散装样品的4-5个数量级。通过表面计算和厚度相关的霍尔测量，我们证明了In2O3薄膜的导电性是由表面供体而不是体积缺陷决定的。
The microscopic cause of conductivity in transparent conducting oxides like ZnO, In2O3, and SnO2 is generally considered to be a point defect mechanism in the bulk, involving intrinsic lattice defects, extrinsic dopants, or unintentional impurities like hydrogen. We confirm here that the defect theory for O-vacancies can quantitatively account for the rather moderate conductivity and off-stoichiometry observed in bulk In2O3 samples under high-temperature equilibrium conditions. However, nominally undoped thin-films of In2O3 can exhibit surprisingly high conductivities exceeding by 4-5 orders of magnitude that of bulk samples under identical conditions (temperature and O-2 partial pressure). Employing surface calculations and thickness-dependent Hall measurements, we demonstrate that surface donors rather than bulk defects dominate the conductivity of In2O3 thin films.