The role of the recombination centers on the modulated photocurrent: Determination of the gap state parameters of semiconductors
The role of the recombination centers on the modulated photocurrent: Determination of the gap state parameters of semiconductors
复制标题
复合中心对调制光电流的作用：半导体能隙态参数的确定
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
P. Kounavis
中科院分区：
文献类型：
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作者：
M. Pomoni;A. Giannopoulou;P. Kounavis
精确表达式的相位调制的光电流（MPC），所谓的Y信号，与一个明确的物理洞察力的状态密度（DOS）光谱推导出没有任何近似。据发现，除了捕获率的多数载流子进入探测的间隙状态，额外的混合贡献的自由多数载流子与捕获的少数载流子的复合过程可能是重要的Y信号的较低的频率。这些额外的贡献阻止了可靠DOS的提取。只要少数载流子被捕获的复合中心的多数载流子的捕获系数与多数载流子被捕获的复合中心的捕获系数相当或高于多数载流子被捕获的复合中心的捕获系数，它们就变得重要。在这种情况下，复合率相对较高，并且来自复合过程的混合贡献可以在实验Y信号中检测到，并且还可以引起相位超前。利用这一特性，当这些复合过程可以忽略不计时，可以通过实验验证，以便安全地提取准确的DOS参数。
Exact expressions for the out of phase modulated photocurrent (MPC), the so-called Y signal, with a clear physical insight for density of states (DOS) spectroscopy are derived without any approximation. It is found that, apart from the capture rate of the majority carriers into the probed gap states, additional mixed contributions from the recombination processes of the free majority carriers with trapped minority carriers may be important for the Y signal of lower frequencies. These additional contributions prevent the extraction of a reliable DOS. They become important as long as the capture coefficient for the majority carriers of the recombination centers, where the minority carriers are trapped, is comparable to or higher than that of the recombination centers were the majority carriers are trapped. In this case, the recombination rate is relatively high and the mixed contributions from the recombination processes can be detectable in the experimental Y signal and may also induce a phase lead. Taking advantage of this behavior it can be experimentally verified when these recombination processes are negligible in order to safely extract the accurate DOS parameters.