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FRINATEK-Fri prosj.st. mat.,naturv.,tek

Point defects and diffusion in semiconducting oxides for renewable energy

Tildelt: kr 2,4 mill.

Transparent conducting oxides (TCO) have received considerable attention during the last few years due to their potential applications as light emitting devices and in photovoltaics. With the combined properties of having close to metallic high electrical conductivity and a high optical transparency in the visible range of the solar spectrum, they are ideally suited for realization of high-efficient solar cells. The potential applications have triggered the need for a fundamental understanding of the elec trical behavior of TCO's, in particular the doping and the mechanisms for charge carrier trapping. In ZnO, for example, theoreticians have tentatively identified several intrinsic and impurity related defects as being electrically active. Experimental ver ification, on the other hand, has so far been hindered by the lack of proper analysis techniques, partially due to the difficulty in making good pn-junctions or Schottky diodes. However, recent progress shows promising results for Schottky contacts of suf ficient quality to pursue ZnO studies using sensitive techniques such as transient capacitance spectroscopy. Moreover, diffusion parameters for intrinsic defects and common residual impurities need to be determined, together with a successful integration with other material systems through heterostructures. In this proposal we will address the issues of (i) electrical, optical and diffusion properties of fundamental point defects in semiconducting oxides, with a particular emphasis on ZnO, (ii) nanostruct uring of TCO's using ion beams, and (ii) TCO based heterostructures.


FRINATEK-Fri prosj.st. mat.,naturv.,tek