School of Material Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
Nano Lett. 2013 Nov 13;13(11):5026-32. doi: 10.1021/nl401702g. Epub 2013 Oct 1.
A comprehensive investigation was carried out on n-type ZnO nanowires for studying the temperature dependence of the piezotronic effect from 77 to 300 K. In general, lowering the temperature results in a largely enhanced piezotronic effect. The experimental results show that the behaviors can be divided into three groups depending on the carrier doping level or conductivity of the ZnO nanowires. For nanowires with a low carrier density (<10(17)/cm(3) at 77 K), the pieozotronic effect is dominant at low temperature for dictating the transport properties of the nanowires; an opposite change of Schottky barrier heights at the two contacts as a function of temperature at a fixed strain was observed for the first time. At a moderate doping (between 10(17)/cm(3) and 10(18)/cm(3) at 77 K), the piezotronic effect is only dominant at one contact, because the screening effect of the carriers to the positive piezoelectric polarization charges at the other end (for n-type semiconductors). For nanowires with a high density of carriers (>10(18)/cm(3) at 77 K), the piezotronic effect almost vanishes. This study not only proves the proposed fundamental mechanism of piezotronic effect, but also provides guidance for fabricating piezotronic devices.
我们对 n 型 ZnO 纳米线进行了全面的研究，以研究从 77 K 到 300 K 的压电器件效应的温度依赖性。一般来说，降低温度会大大增强压电器件效应。实验结果表明，根据 ZnO 纳米线的载流子掺杂水平或电导率，这些行为可以分为三组。对于载流子密度较低的纳米线（77 K 时<10(17)/cm(3)），压电器件效应在低温下占主导地位，决定了纳米线的传输特性；首次观察到在固定应变下，两个接触处的肖特基势垒高度随温度的反向变化。在中等掺杂（77 K 时为 10(17)/cm(3)到 10(18)/cm(3)之间）下，压电器件效应仅在一个接触处占主导地位，因为载流子对另一端正压电极化电荷的屏蔽效应（对于 n 型半导体）。对于载流子密度较高的纳米线（77 K 时>10(18)/cm(3)），压电器件效应几乎消失。这项研究不仅证明了压电器件效应的基本机制，还为压电器件的制造提供了指导。
