Zhang Xie, Shen Jimmy-Xuan, Van de Walle Chris G
Materials Department, University of California, Santa Barbara, California 93106-5050, USA.
Department of Physics, University of California, Santa Barbara, California 93106-9530, USA.
Phys Rev Lett. 2020 Jul 17;125(3):037401. doi: 10.1103/PhysRevLett.125.037401.
Using first-principles approaches we find that the Auger recombination in PbSe is anomalous in three distinct ways. First, the direct Auger coefficient is 4 orders of magnitude lower than that of other semiconductors with similar band gaps, a result that can be attributed to the lack of involvement of a heavy-hole band. Second, phonon-assisted indirect Auger recombination prevails, contrary to the common belief that direct Auger is dominant in narrow-gap semiconductors. Third, an unexpectedly weak temperature dependence of the Auger coefficient is observed, which we can now attribute to the indirect nature of the Auger process. The widely accepted explanation of this behavior in terms of an unusual temperature dependence of the band gap is only a secondary effect. Our results elucidate the mechanisms underlying the anomalous Auger recombination in IV-VI semiconductors in general, which is critical for understanding and engineering carrier transport.
通过第一性原理方法，我们发现PbSe中的俄歇复合在三个不同方面表现异常。首先，直接俄歇系数比具有相似带隙的其他半导体低4个数量级，这一结果可归因于重空穴带未参与其中。其次，与通常认为直接俄歇在窄带隙半导体中占主导地位的观点相反，声子辅助间接俄歇复合占优势。第三，观察到俄歇系数对温度的依赖性出乎意料地弱，我们现在将其归因于俄歇过程的间接性质。关于这种行为基于带隙对温度的异常依赖性这一被广泛接受的解释只是次要效应。我们的结果阐明了一般IV-VI族半导体中异常俄歇复合背后的机制，这对于理解和设计载流子输运至关重要。
