ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Silicon suboxide, SiOx thin films with different oxygen contents (1.15≤x≤1.70) wereprepared by thermal evaporation of silicon monoxide at a residual oxygen pressure of 1·10-3 Pa anddeposition rates of 0.2, 1.0, 3.0 and 6.0 nm/s. Rapid thermal annealing (RTA) of films was carriedout at 1100ºC in vacuum for 15 and 30 s and the films were analyzed by infrared (FTIR) andphotoluminescence (PL) spectroscopy. In the FTIR spectra of SiOx annealed samples, a blue-shift ofthe stretching band with initial oxygen content, x, is observed. This band is shifted to a much lowerfrequency with prolonged RTA time. This behavior can be interpreted in terms of the partialdecrease of oxygen content and film density upon annealing in vacuum. With annealing timeincrease a new band at 1106 cm-1 appears. Therefore, infrared spectra of SiOx films are significantlyaffected by the oxygen content. PL spectra of these films also change drastically with increasingannealing time. In the PL spectra of films annealed for 15 s two bands are easily visible: broad redorangeband at 2.2 eV and a green band at 2.4 eV, while for 30 s annealing only low-energy bandexists. Green band is connected with the defects in the SiOx matrix while red-orange band can bedeconvoluted into several bands at 2.0, 2.3 and 2.5 eV. Two types of defects can be responsible forthe PL band at about 2 eV: defects in a-Si (amorphous silicon) nanoparticles separated during RTA,and nonbridging oxygen hole recombination centers (NBOHC) formed by loosing of oxygen duringRTA. The PL band at 2.3 eV is associated with the defects formed at a-Si/SiOx interfaces while ahardly visible band at 2.5 eV is related to the defects connected with the oxygen deficiency formedin the SiOx matrix during RTA
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/17/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.555.309.pdf
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