Temperature and excitation power dependence of photoluminescence and electrical characterization of Ni-passivated porous silicon

A porous silicon (PS) layer was obtained on p-Si (100) substrate by electrochemical anodization and Ni-porous silicon nanocomposites (Ni-PS) were elaborated by the electrodeposition method using nickel chloride aqueous solution. PS and Ni-PS samples were analyzed by X-ray diffraction (XRD). The XRD patterns revealed the presence of nickel elements in the PS matrix. The investigation by Photoluminescence spectroscopy (PL) enabled us to exam the evolutions of PL peak position, PL intensity, and full width at half maximum (FWHM) as a function of temperature and excitation power density. The modified Arrhenius formula, considering two activation energies, has been used to fit the temperature-dependent integration of PL intensities. PL investigations show that Ni ions cause changes in the recombination process of PS by the creation of new radiative centers as well as the reduction of non-radiative transitions. For Ni-PS nanocomposites, the laser power dependence of the integrated PL intensity shows that the most of transitions are free to bound or bound to bound where as the excitonic transitions are the most dominant in untreated PS. The current-voltage (I-V) characteristics of Ag/PS and Ag/Ni-PS Schottky diodes have been examined. The Cheung method was adopted to extract the parameters of the diode. Experimental results show that the values of ideality factor (n), resistance series (Rs), and barrier height (phi(b)) are affected by the presence of nickel in the porous matrix.