arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1108.0980cond-mat.mtrl-scicond-mat.dis-nn
收藏

ZnO在20- 500 K宽温区的导电过程

Electrical conduction processes in ZnO in a wide temperature range 20--500 K

Chien-Chi Lien, Chih-Yuan Wu, Zhi-Qing Li, Juhn-Jong Lin

摘要:

本文研究了20- 500 K宽温区内生长的ZnO单晶和热循环的ZnO多晶薄膜的导电过程。在110和500 K之间的ZnO单晶的情况下,观察到两种类型的热激活传导过程。这是解释在浅施主和中间深施主的存在下,连续激发的导带,随着温度的升高。通过测量在真空中反复热循环后给定的单晶的电阻率$ρ(T)$,我们表明,氧空位在管理浅施主浓度中起着重要的作用,但留下的激活能($\simeq27\pm$ 2毫电子伏)基本上完好无损。在多晶薄膜的情况下,在$\sim$ 150和500 K之间也观察到两种类型的热激活传导过程。在低于$\sim$ 150 K时,我们发现了一个额外的导电过程,由于最近邻跳跃导电机制发生在浅杂质带。当温度进一步降低到低于$\sim$ 80 K时,观察到Mott可变范围跳跃传导过程的交叉。结合我们以前在2- 100 K温度范围内对ZnO多晶薄膜的$ρ(T)$的测量结果[Y. L.黄{ \it等},J. Appl. Phys. \textbf{107},063715(2010)],该工作建立了从液氦温度到500 K的ZnO材料中的整体导电机制的相当完整的图片。

英文摘要:

We have investigated the electrical conduction processes in as-grown and thermally cycled ZnO single crystal as well as as-grown ZnO polycrystalline films over the wide temperature range 20--500 K. In the case of ZnO single crystal between 110 and 500 K, two types of thermal activation conduction processes are observed. This is explained in terms of the existence of both shallow donors and intermediately deep donors which are consecutively excited to the conduction band as the temperature increases. By measuring the resistivity $ρ(T)$ of a given single crystal after repeated thermal cycling in vacuum, we demonstrate that oxygen vacancies play an important role in governing the shallow donor concentrations but leave the activation energy ($\simeq27\pm$2 meV) largely intact. In the case of polycrystalline films, two types of thermal activation conduction processes are also observed between $\sim$150 and 500 K. Below $\sim$150 K, we found an additional conduction process due to the nearest-neighbor-hopping conduction mechanism which takes place in the shallow impurity band. As the temperatures further decreases below $\sim$80 K, a crossover to the Mott variable-range-hopping conduction process is observed. Taken together with our previous measurements on $ρ(T)$ of ZnO polycrystalline films in the temperature range 2--100 K [Y. L. Huang {\it et al.}, J. Appl. Phys. \textbf{107}, 063715 (2010)], this work establishes a quite complete picture of the overall electrical conduction mechanisms in the ZnO material from liquid-helium temperatures up to 500 K.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑