CHARGE CARRIER TRAPPING AND RECOMBINATION DYNAMICS IN SMALL SEMICONDUCTOR PARTICLES
CHARGE CARRIER TRAPPING AND RECOMBINATION DYNAMICS IN SMALL SEMICONDUCTOR PARTICLES
复制标题
DOI：
10.1021/ja00312a043
复制
发表时间：
1985-12-25
影响因子：
15
通讯作者：
SHARMA, DK
中科院分区：
文献类型：
--
作者：
ROTHENBERGER, G;MOSER, J;SHARMA, DK
利用皮秒或纳秒激光光解激发水溶液中TiO_2胶体粒子（直径120 μ m），我们监测了该激光器中载流子俘获和复合的动力学过程，并用随机动力学模型解释了结果。当俘获电子的吸收光谱出现在30 ps激光脉冲的前沿时，空穴的俘获是一个慢得多的过程，平均需要250 ns。当粒子中电子-空穴对浓度较高时，它们的复合遵循二级规律，速率系数为（3.2±1.4）× 10 - 11 cm ~ 3·s ~（-1）。当载流子占有率很低时，粒子内复合为一级复合，在120 μ m粒径的TiO 2粒子中，单个电子-空穴对的寿命为（30±15）ns。在这些条件下，空穴捕获，大概是由表面羟基，与recombinationand竞争，导致一个产品，其与捕获电子的反应是相对缓慢的。电荷载体介导的光反应的影响进行了讨论。
By using picosecond or nanosecond laser photolysis to excite colloidal (diameter 120 Á) particles of Ti02 in aqueous solution, we have monitored the dynamics of charge carrier trapping and recombination in this semiconductorand interpret the results by a stochastic kinetic model. While the absorption spectrum of the trapped electron appears within the leading edge of the 30-ps laser pulse, the trapping of the hole is a much slowerprocess requiring on the average 250 ns. At high electron-hole pair concentration in the particles, their recombination follows a second order law, the rate coefficient being (3.2±1.4) X 10" 11 cm3 s" 1. Intraparticle recombination becomes first order at very low charge carrier occupancy, the lifetime of a single electron-hole pair in a 120 Á sized TiOz particle being (30±15) ns. Under these conditions, hole trapping, presumably by surface hydroxyl groups, competes with recombinationand leads to a product whose reaction with trappedelectrons is relatively slow. Implications for charge carrier mediated photoreactions are discussed.