Voltage-tunable and two-peak electroluminescence of porous silicon in persulphate solution

摘要

The voltage-tunable electroluminescence (VTEL) of n-type porous silicon (PS) in a persulphate solution under cathodic polarization was studied. A blueshift with the increase of cathodic polarization and a time-dependent redshift at constant potential of EL spectra were observed. To investigate the electroluminescence (EL) mechanism the surface modified method was introduced into the study of EL and the VTEL phenomena for the surface modified PS was also obtained. The results show that the voltage-tunable electroluminescence can be attributed to the selective excitation of different sizes of PS crystallites, which agrees with the quantum confinement model in PS luminescence. At the same time, the two-peak electroluminescence of oxidized PS was obtained.