Effect of oxygen on transient photoconductivity in thin-film Nb x Ti 1¿x O 2
Effect of oxygen on transient photoconductivity in thin-film Nb x Ti 1¿x O 2
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DOI：
10.1103/physrevb.61.8262
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发表时间：
2000-03
影响因子：
3.7
通讯作者：
N. Golego;S. Studenikin;M. Cocivera
中科院分区：
文献类型：
--
作者：
N. Golego;S. Studenikin;M. Cocivera
研究了${\mathrm{Nb}}_{x}}{\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{O}}_{2}$和${\mathrm{TiO}}_{2}$薄膜在${10}^{\ensuremath{-}2}—{10}^{7}\mathrm{s}时间范围内瞬态光导率随温度、光照强度、光照时间和环境成分的变化规律。激发和弛豫瞬态都是缓慢的，并遵循非指数速率定律。提出了一种主要涉及孔洞捕获的电导率模型：${\ mathm {O}}_{2}^{\ mathm {\ensuremath{-}}}$。利用拉普拉斯变换方法可以测定表面空穴捕获引起的自由电子密度和光致表面势垒变化。在氩气中，氧的吸附速率和多余电子到达表面的速率都可能导致衰变，而在空气中只有后者可能是重要的。
Transient photoconductivity in thin-film ${\mathrm{Nb}}_{x}{\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{O}}_{2}$ and ${\mathrm{TiO}}_{2}$ was studied as a function of temperature, light intensity, illumination time, and ambient composition in a time range of ${10}^{\ensuremath{-}2}--{10}^{7}\mathrm{s}.$ Both excitation and relaxation transients were slow and followed a nonexponential rate law. A conductivity model predominantly involving hole capture by ${\mathrm{O}}_{2}^{\mathrm{\ensuremath{-}}}$ at the surface is proposed. It was possible to use a Laplace transform method to determine the free electron density and the photoinduced change in the surface barrier caused by hole capture at the surface. In argon, both the oxygen adsorption rate and the rate at which excess electrons reach the surface may contribute to the decay whereas only the latter may be important in air.