Influence of etching current density on microstructural, optical and electrical properties of porous silicon (PS):n-Si heterostructure

•PS:n-Si heterostucture prepared by photoelectrochemical method.•Meso and micro-pore formation with decreasing crystallinity.•Optical properties indicate quantum confinement in PS pores.•I–V characteristics analyzed and compared with theoretical models for fitment.

In this article effect of etching current density (J) on the microstructural, optical and electrical properties of photoelectrochemically prepared heterostructure is reported. Prepared samples are characterized by FESEM, XRD, UV–Visible, Raman and photoluminescence (PL) spectra and current–voltage (I–V) characteristics. FESEM shows presence of mixture of randomly distributed meso- and micro-pores. Porous layer thickness determined by cross section view of SEM is proportional to J. XRD shows crystalline nature but gradually extent of crystallinity decreases with increasing J. Raman spectra show large red-shift and asymmetric broadening with respect to crystalline silicon (c-Si). UV–visible reflectance and PL show blue shift in peaks with increasing J. The I–V characteristics are analyzed by the conventional thermionic emission (TE) model and Cheung's model to estimate the barrier height (φb), ideality factor (n) and series resistance (Rs) for comparison between the two models. The latter model is found to fit better.