Effect of irradiation on the properties of nanocrystalline silicon carbide films

• Published in: Semiconductors (Woodbury, N.Y.) Vol. 43; no. 10; pp. 1322 - 1327
• Main Authors: Semenov, A. V., Lopin, A. V., Puzikov, V. M., Boriskin, V. N.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01-10-2009
• Subjects: Low-Dimensional Systems; Magnetic Materials; Magnetism; Physics; Physics and Astronomy; 78.66.Li; 81.40.Wx; 61.82.Rx; 78.67.Bf; 78.40.Fy
• ISSN: 1063-7826; 1090-6479
• DOI: 10.1134/S106378260910011X

The effect of irradiation with electrons on the optical and electrical properties of the nanocrystalline rhombohedral 21
R
-SiC and 27
R
-SiC films is studied. The cycles of irradiation of nanocrystalline SiC films on sapphire substrates with electrons with the energy 10 MeV are conducted in the range of fluences from 5 × 10
14
to 9 × 10
19
cm
−2
. It is established that, at the irradiation doses above 10
19
cm
−2
, the optical absorption of the films at the photon energies
E
>
E
g
becomes less efficient than the optical absorption of unirradiated films. It is established that the Urbach energy as a function of the irradiation dose exhibits a minimum at the dose ∼10
17
cm
−2
for the 21
R
-SiC films and ∼5 × 10
17
cm
−2
for the 27
R
-SiC films, suggesting that radiation induces some ordering in the films. As the dose is increased from 5 × 10
17
up to 9 × 10
19
cm
−2
, an increase in the Urbach energy and a decrease in the optical band gap are observed. The effect is attributed to an increase in the concentration of radiation defects in the films.