Temperature Dependence of Photoluminescence Spectra from Crystalline Silicon

Abstract

Photoluminescence (PL) spectra from lightly boron (B) doped p−-Si(100) under 488.0 nm Ar+ ion laser excitation over the temperature range of 22 K–290 K is presented. Change of PL peak height (maximum intensity), peak position, peak area (areal intensity), full-width-at-half-maximum (FWHM: peak width) were determined as a function of temperature. PL intensity was sharply decreased with temperature increase in the temperature range of 22 K – 170 K and then slowly increased again in the temperature range of 170 K–290 K. Phonon replicas of a relatively sharp band-to-band (or band edge (BE)) PL peak were clearly measured at low temperatures (≤90 K). PL spectra became broader and the phonon replicas were barely distinguishable as the temperature was increased. The envelope of the main PL peak and the broadening of peak width with the Si temperature were qualitatively in good agreement with the Maxell-Boltzmann probability distribution function. The direction of peak position shift with Si temperature change was also in good agreement with the temperature dependence of the Si bandgap. All measured PL spectra were curve fitted using combinations of modified Gaussian function(s) and standard Gaussian function(s). A simplified curve fitting method for broad PL spectra, consisting of the BE peak and band tail peak, using an exponentially modified Gaussian (EMG or ExGaussian) function and a number of standard Gaussian functions, was proposed from a practical usage point of view. Radiative recombination processes in Si and potential industrial applications of the PL characterization technique were discussed.