Porous nanostructured layers on germanium produced by Laser optical breakdown processing

摘要

Germanium wafer surface is modified by a technique of CO_2-laser induced air breakdown processing, which was recently introduced and used to produce photoluminescent Si-based nanostructured layers. Structural and optical properties of the Ge-based layers, formed under the irradiation spot as a result of the processing, are characterized by different techniques (SEM, XPS, FTIR, XRD, and PL). It has been found that the layers present a porous structure, containing nanoscale holes, and consist of Ge nanocrystals embedded into GeO_2 matrices. They exhibited strong photoluminescence (PL) in the green range (2.2 eV), which was attributed to defects in GeO_2 matrix due to the presence of Ge-O modes with some OH vibration in the FTIR spectra. The layers are of importance for local patterning of nanostructures on semiconductors.