Morphology of porous n-type silicon obtained by photoelectrochemical etching II. Study of the tangled Si wires in the nanoporous layer

Visible luminescence observed from the nanoporous layer of the two (100)-orinted low doped and highly doped PEC-etched n-type Si is explained as being due to the existence of single crystal silicon quantum wires within their structure. The nanometer-size tangled Si structure is contained and attached to a regular geometric Si macroarray. TEM studies also reveal subtle variations in morphology between the two layers studied, which could explain the blueshift in the spectrum of the low-doped specimen - thinner and more rigid irregular wires - as compared to the highly doped specimen.