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RADIATIVE CENTERS FORMED BY HALOGEN MOLECULES INTERCALATED IN MoS2 AND WS2 LAYERED SEMICONDUCTORS

D. Dumchenko1, C. Gherman1,* , L. Kulyuk1

Affiliation

  1. Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, Moldova

Abstract

The study of the steady-state and time resolved photoluminescence of 2H-MoS2:Cl2 and 2H WS2:Br2 crystals is presented. For both investigated materials two distinct spectral regions was identified: the excitonic region, located in the vicinity of the indirect band gap and consisting of several sharp zero-phonon lines and their phonon replica, and the vibronic broad band IR region, characteristic also for natural crystals without halogen impurities. The thermal quenching of the exciton emission at T>60K was also observed. The strong sharp photoluminescence line of the indirect band gap semiconductors is attributed to the recombination of excitons bound on electron-attractive neutral centers, formed due to the intercalation of the halogen molecules in the van der Waals gap of the layered compound. In the framework of a kinetic model for a compensated semiconductor in thermal equilibrium, the temperature behaviour of the excitonic spectral line intensities, radiative decay time and the thermal quenching process of the bound exciton emission are described..

Keywords

MoS2 Layered semiconductors, Photoluminescence, Radiative centers, Halogen molecules.

Submitted at: June 8, 2004
Accepted at: March 23, 2005

Citation

D. Dumchenko, C. Gherman, L. Kulyuk, RADIATIVE CENTERS FORMED BY HALOGEN MOLECULES INTERCALATED IN MoS2 AND WS2 LAYERED SEMICONDUCTORS, Journal of Optoelectronics and Advanced Materials Vol. 7, Iss. 2, pp. 775-779 (2005)