Abstract: In this paper we examine the use of a high-power, tunable free-electron laser (FEL) source to measure photoluminescence (PL) and photoluminescence excitation (PLE) spectra in two classes of disordered semiconductors, amorphous semiconductors and partially ordered III-V ternary semiconductors. The source must be tunable to follow the absorption continuously across the region of the optical energy gap, and the source must be of high power to provide enough absorbed photons in this relatively transparent spectral region so that PL processes can be measured. The usefulness of PLE spectroscopy in these semiconducting thin films lies in the fact that if the quantum efficiency $eta for the PL process is independent of energy, then the PLE spectrum is a measure of the optical absorption. In addition, disordered semiconductors often exhibit enhanced absorption below the optical gap due to the disorder itself. PLE measurements that probe regions where the absorption coefficient $alpha is small ($alpha $LS $LS 10$+3$/ cm$+$MIN@1$/) are most important because in these regions $alpha is dominated by the electronic states introduced by the disorder. !7
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机译：摘要：在本文中，我们研究了使用高功率可调谐自由电子激光（FEL）源来测量两类无序半导体，非晶半导体和部分有序半导体中的光致发光（PL）和光致发光激发（PLE）光谱-V三元半导体。该源必须是可调谐的，以在光能隙的整个区域内连续跟踪吸收，并且该源必须具有高功率，以在此相对透明的光谱区域中提供足够的吸收光子，以便可以测量PL过程。 PLE光谱学在这些半导体薄膜中的有用之处在于，如果PL过程的量子效率$η与能量无关，那么PLE光谱就是对光吸收的度量。另外，由于无序本身，无序半导体通常在光学间隙以下显示出增强的吸收。 PLE测量探测吸收系数$ alpha小的区域（$ alpha $ LS $ LS 10 $ + 3 $ / cm $ + $ MIN @ 1 $ /）是最重要的，因为在这些区域中，$ alpha被电子控制由疾病引入的状态。 ！7
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