Efficient Visible Electroluminescence from Porous Silicon Diodes Passivated by Carbon Films

By using n-butylamine as a carbon resource, carbon film is deposited on the p-n porous silicon (PS) surface with a radio-frequency glow discharge plasma system. Raman spectra and infrared reflection (IR) spectra of the carbon films indicate that there are amine-group and hydrogen atoms therein. The IR spectra of the passivated PS samples exhibit that the PS surfaces are mainly covered with Si-C,Si-N and Si-O bonds. Electroluminescece (EL) spectra show that EL intensity of the passivated PS diodes increases greatly and the blueshift of EL peak occurs compared with the diodes without treatment and both of them are stable while the passivated diodes are exposed to the air indoor. The I-V characteristics reveal that the passivated diodes have a smaller series resistance and a lower onset voltage. The influence of the carbon film passivation on EL properties of porous silicon has also been discussed. The results have proved that the carbon film passivation is a good way to enhance the PS luminescent intensity and stability.