Low temperature electrical transport in thin carbon films deposited on SiO2/Si substrates by pulsed laser deposition
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2023-05-01 |
| Journal | Journal of Physics Conference Series |
| Authors | E. Valcheva, Širil Širilov, Anna Dikovska, T. I. Milenov |
| Institutions | Sofia University āSt. Kliment Ohridskiā, Bulgarian Academy of Sciences |
| Citations | 1 |
Abstract
Section titled āAbstractāAbstract In this paper electrical transport studies are performed on thin carbon films deposited on SiO 2 /Si substrates by pulsed laser deposition (PLD) applying laser ablation of micro-crystalline graphite target. Experiments were carried out on 320 - 420 nm thick SiO 2 on Si substrates as well as on hydrogenated diamond-like carbon (DLC) films deposited on SiO 2 /Si. Structural studies by means of XPS, SEM and Raman spectroscopy revealed that the films can be characterized as nano-sized carbon phases possessing different phase composition (i.e. the ratio sp 3 /sp 2 hybridized carbon, etc.). The electrical conductivity/resistivity of the films was measured in the temperature range 10 K < T < 300 K. Four-contact Van der Pauw method as well as two contact schemes have been applied. Some films have low room temperature resistivity in the range Ļ = (0.1-1.5)Ć10 -3 Ī©.Ā·m and consist predominantly of sp 2 hybridized carbon with Raman spectra, which resemble that of nano-sized graphene depending on the deposition conditions and substrates used. The thinnest only 0.5 nm layer deposited directly on SiO 2 exhibits relatively low specific resistance (~10 -3 Ī©. m), which can be taken as an indication of good deposition conditions of graphene-like layers. The current flow mechanism was explored at temperatures from 300 K down to 10K. The temperature dependence reveals non-metallic behavior - the conductivity decreases at decreasing temperature as opposed to typical metal behaviour. A model of variable range hopping (VRH) mechanism is applied to explain the low temperature conductivity drawn from transport in nanocrystalline disordered systems.