Electronic properties of hydrogenated amorphous carbon films deposited using ECR-RF plasma method |
| |
| Affiliation: | 1. Laboratoire de Physique de la Matière Condensée, Faculté des Sciences d''Amiens, 33 Rue Saint-Leu, 80039 Amiens, France;2. Laboratoire de Génie Electrique de Paris (URA 0127 CNRS) SUPELEC, Plateau de Moulon, 91192 Gif sur Yvette, France;3. Groupe de Physique des Solides (UMR 17 CNRS), Universités Paris VII et VI, 2 place jussieu, 75251 Paris cedex 05, France;1. The Center for Pediatric Liver Diseases, Children''s Hospital of Fudan University, Shanghai, China;2. Department of Pathology and Laboratory Medicine, Cincinnati Children''s Hospital Medical Center, Cincinnati, Ohio;3. Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio;4. Institutes of Biomedical Sciences, Fudan University, Shanghai, China;5. Shanghai Key Laboratory of Birth Defect, Shanghai, China;1. State Key Laboratory of Bioreactor Engineering & Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, PO Box 268, 130 Meilong Road, Shanghai 200237, PR China;2. Department of General Surgery, Xinhua Hospital, Shanghai Jiaotong University, 1665 Kongjiang Road, Shanghai 200092, PR China |
| |
| Abstract: | A combination of junction capacitance, electron spin resonance and electrical conductivity measurements are used to investigate the electronic properties of two different types of a-C:H films grown in a dual ECR-RF glow discharge system at substrate bias equal to −30 and −600 V, respectively. The analysis of the steady state admittance (both capacitance C and conductance G) as a function of frequency (ω=5 Hz–1 kHz) and temperature (20–350 K) allows an estimate of the density of states at the Fermi level of approximately 7×1015 and 9.7×1016 eV−1 cm−3 for the −30 and −600 V deposited samples, respectively, values well below those deduced for the density of spins from the electron spin resonance experiments, of approximately 1019–1020 cm−3. Concerning the conductance results, two transport processes operating, respectively, below and above 290 K are shown. The high temperature process is associated with an activation energy of 0.5 and 0.41 eV for the −30 and −600 V samples, respectively, in good agreement with the values obtained in the high temperature range (>300 K) for the activation energy of the electrical conductivity. Regarding the effect of the frequency and temperature on the conductance, we show that for temperatures below 290 K, a Variable Range Hopping mechanism is possible by facing our data to the Mott's model. Annealing at high temperature induces structural changes accompanied by an increase in the spin density in both types of samples with however, a different behaviour from one type to another. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
