Open AccessФормирование светоизлучающих в ИК-диапазоне нанокристаллов германия в плeнках Ge:SiO-=SUB=-2-=/SUB=-
Author(s) -
В. А. Володин,
Rui Zhang,
Г.К. Кривякин,
A. Kh. Antonenko,
M. Stoffel,
H. Rinnert,
M. Vergnat
Publication year - 2018
Publication title -
fizika i tehnika poluprovodnikov
Language(s) - English
Resource type - Journals
eISSN - 1726-7315
pISSN - 0015-3222
DOI - 10.21883/ftp.2018.09.46156.8815
Subject(s) - nanoclusters , amorphous solid , photoluminescence , materials science , annealing (glass) , germanium , crystallization , nanocrystal , raman spectroscopy , analytical chemistry (journal) , crystallography , silicon , chemical engineering , nanotechnology , optoelectronics , chemistry , optics , metallurgy , physics , chromatography , engineering
The study is concerned with light-emitting Ge nanocrystals formed during the annealing of Ge_ x [SiO_2]_1 –_ x films produced by the high-vacuum cosputtering of germanium and quartz targets onto substrates at a temperature of 100°C. In accordance with the conditions of growth, the Ge molar fraction was varied from 10 to 40%. By means of electron microscopy and Raman spectroscopy, amorphous Ge nanoclusters ~4–5 nm in dimensions are detected in as-deposited films with a Ge content higher than 20 mol %. To crystallize amorphous nanoclusters, annealing at temperatures of up to 650°C is used. The kinetics of the crystallization of Ge nanoclusters is studied, and it is established that up to ~1/3 of the amorphous phase is retained in the system, supposedly at the interfaces between nanocrystals and the surrounding amorphous SiO_2 matrix. It is found that, upon annealing in normal atmosphere, germanium nanoclusters are partially or completely oxidized (at a Ge molar fraction of 30% and smaller). An intense infrared photoluminescence signal from quantum-confined Ge nanocrystals and a visible photoluminescence signal defined by defect complexes (oxygen vacancy + excess Ge atoms) are observed.