Effects of hydrogen and helium dilution on the optical band gap and photoluminescence of DC PECVD hydrogenated amorphous carbon films
Document Type
Article
Publication Date
1-1-2008
Abstract
A series of hydrogenated amorphous carbon (a-C:H) thin films were deposited using home-built direct-current (DC) plasma enhanced chemical vapour deposition (PECVD) system. The a-C:H thin films were deposited using pure methane (CH 4) gas diluted either with hydrogen (H) or helium (He). The effects of hydrogen and helium dilution on the photoluminescence (PL) properties and optical band gap (E-04) were studied. The dependence of PL properties and optical energy gap on the film thickness has also been investigated. The characterization techniques used were optical transmission and photoluminescence spectroscopies. The sp(2) cluster sizes were determined from Raman spectra are in the range of 5 to 7 nm. Hydrogen and helium. dilution of methane strongly influences the PL efficiency of the a-C:H films. The PL efficiency are enhanced with increase in film thickness for a-C:H films prepared both from H and He diluted CH4. The optical energy gap of these films decreases with increase in H or He dilution and film thickness.
Keywords
hydrogenated amonphous carbon hydrogen and helium dilution photoluminescence optical band gap
Divisions
PHYSICS
Publication Title
Sains Malaysiana
Volume
37
Issue
3
Publisher
Penerbit Universiti Kebangsaan Malaysia