Below Gap Excitation of Photoluminescence in a-Si:H


PL measurements on device-quality samples of a-Si:H (dark ESR bulk signal, Ns < 3 × 1015spins/cm3) and on a sample with Ng = 1016 spins/cm3 have been performed using excitation energies, E×, from approximately 1.3 to 2.4 eV. Sample temperatures investigated cover the range 4 to 300 K, and PL energies both below and above the excitation energies were measured. PL spectra were recorded from approximately 0.7 to 1.8 eV with a dynamic range exceeding 1012 at constant incident power density. The results permit the separation of the one-photon (band-tail to band-tail) and two-photon (two consecutive excitations through silicon dangling bonds) excitation processes. In contrast to the well-known, strong temperature dependence of the PL efficiencies near the PL peak, the PL at the highest energies (> 1.7 eV) depends only weakly on the temperature at constant Ex

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Yin, X., Raikh, M.E. & Taylor, P.C. Below Gap Excitation of Photoluminescence in a-Si:H. MRS Online Proceedings Library 377, 167–172 (1995).

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