Silicon carbide (SiC) is a non-oxide high-temperature stable and extremely corrosion resistant semiconductor. Its high charge mobility and high breakdown electric field, and also the fact that according pn-junctions can operate up to 600°C, make it a desirable material for high-power and high-temperature electronics. Like transparent (semi-)conducting oxides, also silicon carbide comprises a wide band gap, enabling its use as transparent conductor or semiconductor in photovoltaic or light emitting devices. However, despite these advantages, it is rarely used on larger scale for optoelectronics. The major reason for this is its costly production via sublimation-based single crystal growth or thin film epitaxy, the two methods of choice. Additionally, the introduction of dopants, especially p+ is rather difficult, ion-implantation caused lattice defects hard to heal.
Here, we present an alternative fabrication approach to semiconductor-grade silicon carbide materials, derived by sol-gel processing combined with a carbothermal reduction. We will show that this versatile method allows the preparation of crystalline SiC in various forms, as e.g. small particles, porous bulk structures, foams, nanowires or dense thin films. The liquid precursor even enables infiltration and solution deposition techniques, just like common sol-gel techniques for oxides. If required, we achieve n- or p- doping of SiC by addition of suitable compounds at the wet-chemical stage, which are built into the SiC lattice in-situ during formation. Results on essential properties of this sol-gel SiC material for its use in semiconductor applications will be presented, such as morphology, surface termination, defects and impurities. Exemplarily, we will demonstrate its functionality for organic-inorganic hybrid solar cells, where it qualifies as inorganic acceptor in combination with a photoactive polymer donor, and its potential for photocatalytic processes such as electrochemical carbon dioxide conversion.
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|Präsentation||sol-gel SiC scheme||Sol-gel silicon carbide semiconductor: precursor, n- (green) and p-doped (blue) 3C-SiC microcrystals; the art of a porous structure (SEM); and photovoltaic device characterization.||209 KB||Download|