The capacitance–voltage measurement of the screen-printed silicon solar cells with electrochemically etched nanostructured porous silicon antireflection coating

In the present study, capacitance–voltage measurement of screen-printed silicon solar cells with electrochemically etched nanostructured porous silicon structure has been investigated. The structural and optical properties of the freshly etched as well as thermally oxidized porous silicon surfaces was characterized by FTIR, Raman spectroscopy, photoluminescence and atomic force spectroscopy measurements. The values of the doping level, NA ≅ 8.4 × 1016 atoms cm−3 in the bulk Si substrate and the built-in potential, Vbi = 0.91 V was estimated by extrapolating the plot of the inverse-square capacitance–reverse bias voltage (I/C2–VR plot). The impedance spectra indicate a significant change in the frequency response of thermally oxidized porous silicon surface which is more distinct in the lower frequency range. The Raman spectra of the etched porous silicon has a sharp peak with a broadening and downshift of phonon energy which indicates that porous silicon is characterized by a nanoscale distribution of the pores and crystallites network and, thereby giving a detailed description on the ‘quantum confinement model’ for the light emission in the visible range from electrochemically etched porous silicon structure.