REESTABLISHMENT OF PHOTOLUMINESCENCE IN CU QUENCHED POROUS SILICON BY ACID TREATMENT

HCl, H3PO4, and H2SO4 baths have been used to re-establish the photoluminescence of porous Si whose initial luminescence had been quenched by immersion in CuCl2. HCl had the fastest effect, with luminescence beginning to reappear after typically a few minutes, while the other acids required typically one to two days for dim luminescence to start reappearing. Auger electron spectroscopy (AES) depth profiling showed that after quenching, the Cu profile typically penetrated 2000 to 3000 Å into the porous Si and that the O concentration was greatly enhanced in this region. After re-establishment of the luminescence by acid treatment, the AES depth profiles showed no Cu, but still had an enhanced O region of similar size and concentration. Photoluminescence emission spectra taken in situ during acid treatment with HCl showed a redshift of about 8% in the peak wavelength as the intensity increased. © 1995 American Institute of Physics.