"

Cookies ussage consent

Our site saves small pieces of text information (cookies) on your device in order to deliver better content and for statistical purposes. You can disable the usage of cookies by changing the settings of your browser. By browsing our site without changing the browser settings you grant us permission to store that information on your device.

I agree, do not show this message again.

Phototransport and photoluminescence in nanocrystalline porous silicon

V. IANCU1, M. L. CIUREA2,* , I. STAVARACHE1, V. S. TEODORESCUa2

Affiliation

  1. Department of Physics, University “Politehnica” of Bucharest, Bucharest 060042, Romania
  2. National Institute of Materials Physics, 077125 Bucharest - Măgurele, P.O. Box MG-7, Romania

Abstract

The paper presents the phototransport and photoluminescence investigations on nanocrystalline porous silicon. Spectral dependence curves of the phototransport and photoluminescence were taken at room temperature. A typical phototransport curve presents several maxima and shoulders, while the photoluminescence curves present only one maximum. The temperature dependence of the phototransport was measured in the 85 – 250 K range for different wavelengths. All these curves present only one activation energy on the whole temperature interval. The experimental results are interpreted taking into account a quantum confinement model. Previous microstructure investigations proved that the studied nanocrystalline porous silicon is formed by a nanowire network. Then, the electron Hamiltonian can be split into the sum of a 1D longitudinal Bloch part and a 2D transversal part, the nanowire wall acting like a potential well. Thus, a number of discrete energy levels will appear into the band gap. Both phototransport and photoluminescence maxima are due to the transitions between these levels, corresponding to a mean nanowire diameter of 3.2 nm, in good agreement with the previous microstructure and electrical transport investigations. On the contrary, the temperature dependence of the phototransport is determined by the surface states located on the internal surface and/or the interface between nanocrystallites..

Keywords

Nanocrystalline porous silicon, Phototransport, Photoluminescence, Quantum confinement.

Submitted at: Jan. 15, 2007
Accepted at: Aug. 18, 2007

Citation

V. IANCU, M. L. CIUREA, I. STAVARACHE, V. S. TEODORESCUa, Phototransport and photoluminescence in nanocrystalline porous silicon, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 8, pp. 2638-2643 (2007)