Effect of chemical treatment on photoluminescence spectra of SiO x layers with built-in Si nanocrystals
- PDF / 261,111 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 89 Downloads / 210 Views
N, TREATMENT, AND TESTING OF MATERIALS AND STRUCTURES
Effect of Chemical Treatment on Photoluminescence Spectra of SiOx Layers with Built-in Si Nanocrystals I. Z. Indutnyy^, I. Yu. Maœdanchuk, V. I. Min’ko, P. E. Shepelyavyœ, and V. A. Dan’ko Lashkarev Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev, 03028 Ukraine ^e-mail: [email protected] Submitted December 28, 2006; accepted for publication March 13, 2007
Abstract—The effect of chemical treatment in saturated vapors of ammonia and acetone on the spectral composition and intensity of photoluminescence in porous SiOx films containing Si nanocrystals (nc-Si) is studied. The porosity of the SiOx films is provided by oblique vacuum deposition of thermally evaporated silicon or silicon monoxide on polished silicon substrates. The kinetics of adsorption of the vapors is monitored by variations in the frequency of a quartz oscillator on which the films to be studied are deposited. As a result of chemical treatment followed by high-temperature annealing of the SiOx films at the temperature 950°C, a new band, absent from the as-prepared films, appears in the photoluminescence spectrum at shorter wavelengths. The peak position and intensity of the band depend, correspondingly, on the composition of the film and on the time duration of the treatment. It is found that the new photoluminescence band is quenched upon exposure to laser radiation at the wavelength 488 nm. The quenching is more pronounced at the band peak. The possibility of controlling the characteristics of photoluminescence of the porous structures by chemical treatment is shown. PACS numbers: 78.55.Mb, 79.60.Jv, 81.40.Ef DOI: 10.1134/S1063782607100223
1. INTRODUCTION Thin-film structures containing Si nanocrystals (ncSi) embedded in the SiOx matrix attract the attention of many researchers, since the materials show promise for the production of light-emitting devices by the highly developed low-cost silicon technology [1–4]. The advantages of the nc-Si–SiOx nanocrystalline composites over porous Si are their mechanical and chemical stability and the complete compatibility with presentday silicon technology. In most cases, such structures are produced in a two-stage process. At first, the nonstoichiometric SiOx oxide films are deposited, and then the resulting layers are annealed at high temperature. As a result, Si nanoclusters 1–5 nm in size are formed in the oxide matrix. The structure of the nanoparticles depends on the annealing temperature: annealing at temperatures below 900°C results in the formation of amorphous inclusions, whereas at higher temperatures, the Si nanocrystals are formed, with the electronic structure modified by the quantum-confinement effect [1, 2, 4]. Depending on the dimensions of the nc-Si clusters formed in the matrix, their concentration, and the quality of the nc-Si–matrix interface, such composite films can exhibit photoluminescence (PL) in the near-infrared and visible spectral regions. With decreasing dimensions of the nanoclusters, the p
Data Loading...
