ISSN:
1432-0630
Schlagwort(e):
PACS: 72.20; 72.80; 78.65
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
,
Physik
Notizen:
Abstract Fine-grained (d≈0.1 μm), polycrystalline SiC films were prepared on top of insulating and optically transparent sapphire substrates by means of a thermal crystallization technique. Optical absorption measurements indicate that the individual SiC grains consist of relatively defect-free β-SiC surrounded by high-defect density grain-boundary material. Nominally undoped material exhibits a low dc conductivity (σ≈10-8Ω-1 cm-1) in the dark and an efficient photoconductivity upon illumination with short-wavelength UV light. The temperature dependence of the dc transport exhibits a quasi-Arrhenius-type behaviour with average activation energies of the order to 0.6 eV. A characteristic feature of this kind of transport is a continuous increase in activation energy with increasing film temperature. Upon doping with N, P and Al ions, the average activation energy is decreased and room temperature conductivities of the order of 0.1 Ω-1 cm-1 are reached. Doping with B ions, on the other hand, only leads to high-resistivity material. It is shown that the electronic transport in doped SiC-On-Sapphire (SiCOS) films can be successfully modelled in terms of a grain-boundary-dominated conduction process. In this process thermal activation across potential barriers at the grain-boundary surfaces competes with tunneling through these same barriers.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/s003390050190
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