Electrical and optical properties of porous silicon

ABSTRACT In this work, porous silicon has been obtained by electrochemical anodization of single crystal silicon wafers of both n and p type. The thicknesses of the samples are around 10- 30(j,m. When some ultraviolet light is shed on the porous silicon films, it has been observed that it emits visible orange photoluminescence. The variations in the photoluminescent intensities of the samples depending on the wavelength have been measured and the way the intensity of the photoluminescence changes examined as a result of the annealing of the sample. A thin film layer has been separated from the surface of the sample in order to explore the optical characteristics. The reflection and absorption coefficients of the films have been calculated from the long wavelength optical spectra of the films (T=f(v)) in the Fourier Transform Infrared (FTIR) spectroscopy. To investigate the variations of the absorption coefficients of films depending on the amount of annealing, the curves T=f(v) have been obtained by annealing the films at different temperatures and how annealing effects the structure of the porous silicon examined. Having achieved the optical spectra in short wavelengths, the band gaps of both single crystal and porous silicon samples calculated and the effect of annealing on the transmission examined. After the investigation of the current- voltage characteristics of the samples with or without light, the variation of the saturation current with temperature, the barrier height 3>b and ideality factor n have all been calculated and at the same time the resistivity of the porous silicon found. IX