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Origin of photoluminescence in tetrahedrally-bonded amorphous semiconductors and amorphous chalcogenides♣

TAKESHI AOKI1,*

Affiliation

  1. Joint Research Centre of High-technology, Graduate School of Electronics, Tokyo Polytechnic University, Atsugi 243- 0297, Japan

Abstract

Using wideband quadrature frequency resolved spectroscopy (QFRS) expanded for lifetime measurement from 2 ns to 160 s, we have revealed that the lifetime distribution of the photoluminescence (PL) of a-Si:H is a triple-peak structure having the third peak at a lifetime ≥ 0.1 s, instead of the well-known double peaks at ∼μs and ∼ms. Moreover, the triple-peak phenomenon has been found to occur universally among non-crystalline semiconductors such as a-Ge:H and a-SiN:H, and chalcogenide glasses. The dependences of the QFRS spectra on temperature, excitation intensity and energy, emission energy and magnetic fields have elucidated that both geminate or excitonic recombination and non-geminate, or distant pair (DP) recombination co-exist in PL of non-crystalline semiconductors, which has settled the controversy as to whether the recombination is germinate or non-geminate in the PL. Observing the residual PL decay together with the QFRS in a-Si:H, we have also resolved the long-standing disagreement between the PL and light-induced electron spin resonance (LESR) signal. In addition, the paper presents the different effects of electric field on the two types of recombination..

Keywords

Exciton, Radiative transition time, Geminate and nongeminate (DP) recombination, LESR, Effective temperature.

Submitted at: Nov. 5, 2008
Accepted at: Sept. 9, 2009

Citation

TAKESHI AOKI, Origin of photoluminescence in tetrahedrally-bonded amorphous semiconductors and amorphous chalcogenides♣, Journal of Optoelectronics and Advanced Materials Vol. 11, Iss. 9, pp. 1044-1052 (2009)