Morphology and stress study of nanostructured porous silicon as a substrate for PbTe thin films growth by electrochemical process

porous silicon layers (psl) were produced by stain etching from a hf:hno3 500:1 mixture with etching time varying in the range of 1 up to 10 min. the samples have presented nanometric porosity as a function of etching time, characteristic of heavily doped p type silicon. the residual stress and the correlation length of the layers were obtained through the analysis of the micro-raman spectra using a phonon confinement model including a term to account for the amorphous phase. the residual compressive stress tends to increase as expected due to the contribution of smaller crystallites to be more representative as the etching time increases. pbte thin films were electrodeposited on psl from aqueous alkaline solutions of pb(ch3coo)2, disodium salt of ethylendiaminetetraacetic acid (edta) and teo2 by galvanostatic and potentiostatic method. it was also obtained nanostructured pbte thin films with polycrystalline morphology evidenced by x-ray diffraction (xrd) spectra. scanning electron microscopy (sem) analysis has demonstrated good films reproducibility with an average grain size of 100 nm.