Near-infrared photoluminescence and micro-Raman study of spark discharge germanium nanoparticles

Abstract We report the investigation of near-infrared (NIR) photoluminescent and structural properties of aerosol germanium nanoparticles, synthesized by spark discharge method followed by sintering in a tube furnace at different temperatures varying from 25 to 750 °C. We demonstrate a growth of mean primary particle size and change in morphology from agglomerates of germanium nanocrystals in amorphous matrix to individual pure crystal germanium nanoparticles with temperature increase. Pure germanium nanoparticles were prepared at temperatures above 600 °C and distinguished by absence of near-infrared photoluminescence. According to Raman spectroscopy the presence of amorphous germanium in the samples, sintered at 25 to 450 °C, leads to appearance of the luminescence in infrared region with intensity increase from 1100 to 1550 nm.