Temperature-dependent transport properties of hydrogen-induced diamond surface conductive channels
Temperature-dependent transport properties of hydrogen-induced diamond surface conductive channels
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DOI：
10.1103/physrevb.71.245310
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发表时间：
2005-06
影响因子：
3.7
通讯作者：
J. Garrido;T. Heimbeck;M. Stutzmann
中科院分区：
文献类型：
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作者：
J. Garrido;T. Heimbeck;M. Stutzmann
在氢终止诱导的金刚石表面导电沟道中进行了霍尔效应实验。研究了电导率和霍尔迁移率随温度和载流子浓度的变化。电导率和霍尔迁移率随温度呈指数关系激活，激活能几乎相同，而载流子浓度与温度无关或仅表现出很弱的温度依赖关系，正如金属导电所预期的那样。发现激活能随载流子浓度的增加而减小，直至接近于零。实验结果是在一个基于大范围电势起伏的模型框架内讨论的，该起伏导致金属和绝缘区在金刚石表面共存。用渗流理论分析了薄膜的电导率和霍尔迁移率。在渗流阈值以下，通过热激发跨越分隔金属区域的势垒进行输运。在渗流阈值以上，由于剩余势垒上方的热发射有助于降低长渗流路径的阻力，激活的输运持续存在。实验结果用三个自由参数模型进行了拟合：金属导电率和迁移率、平均势垒和绝缘区占据的表面积分数。金属区域的霍尔迁移率随着载流子浓度的增加而减小，这表明表面散射的影响很大。文中还讨论了在极低温度下变程跳跃的贡献。
Hall effect experiments have been carried out in diamond surface conductive channels induced by hydrogen termination. The conductivity and the Hall mobility have been studied as a function of temperature and carrier concentration. The conductivity and Hall mobility are exponentially activated with temperature, with almost identical activation energies, whereas the carrier concentration shows no or only a very weak temperature dependence, as expected for metallic conduction. The activation energy is found to decrease with increasing carrier concentration, until it almost vanishes. The experimental results are discussed in the frame of a model based on large-range potential fluctuations which give rise to metallic and insulating regions coexisting at the diamond surface. The conductivity and Hall mobility are analyzed using percolation theory. Below the percolation threshold, transport occurs by thermal excitation over the potential barriers separating the metallic regions. Above the percolation threshold, activated transport persists as the thermal emission over remaining potential barriers contributes to reduce the resistance of long percolating paths. The experimental results have been fitted using a model with three free parameters: metallic conductivity and mobility, averaged potential barrier, and surface fraction occupied by insulating regions. The Hall mobility in the metallic regions has been found to decrease with increasing carrier concentration, indicating a strong influence of surface scattering. The contribution of variable-range hopping at very low temperatures is also discussed.