Observation and enhancement of visible photoluminescence of PECVD a‐SiOx:H (x < 2) thin films by microcavity effect

Abstract

Abstracta‐SiOx:H (x < 2) thin film samples prepared in a PECVD system by using SiH4+CO2 gas mixture show strong room temperature visible photoluminescence (PL) at a photon energy of 2.1 eV. The PL spectrum of a single layer sample was observed to reshape due to the multiple reflection between two interfaces of the film. The orders of the resonance modes in the PL spectrum range of 1.5 eV‐2.5 eV, were calculated to be within a range of m=8 to m=13. The peak energy of the most intense mode (m=11) was observed at 2.1 eV and the half width and the quality factor of the microcavity were calculated as Δν=20 THz and Q=20, respectively. Two multi‐layered distributed Bragg reflectors (10 and 25 layer pairs) were fabricated with two different refractive indices (n1=3.2 and n2=2.4) of the layers with λ/4 (λ0=580nm) optical thickness. The PL intensity was detected increasing in intensity around the photon energy of 2 eV and the other modes were suppressed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)