The effect of high dose vanadium ion implantation and pulsed laser annealing on the crystal structure and sub-bandgap optical absorption features of V-supersaturated silicon samples has been studied through the combination of experimental and theoretical approaches. The interest of V-supersaturated Si relies on its potential as a material having a new-band within the Si bandgap. Rutherford backscattering spectrometry (RBS) measurements and computed formation energies through quantum calculations, evidence that V atoms are mainly located at interstitial positions. The response of sub-bandgap spectral photoconductance is extended far in the infrared region of the spectrum.
Theoretical simulations (based on Density Functional Theory and many-body perturbation in GW approximation) bring to light that, in addition to V atoms at interstitial positions, Si defects should be also taken into account to explain the experimental profile of the spectral photoconductance. The combination of experimental and theoretical methods evidences that the improved spectral photoconductance up to 6.2 µm (0.2 eV) is due to new sub-bandgap transitions, for which the new band due to V atoms within the Si bandgap plays an essential role. This enables the use of V-supersaturated silicon in the third generation of photovoltaic devices.
Garcia-Hemme, E., García, G., Clemente, P.P., Montero, D., Hernansanz, R.G., Diaz, G.G. and Wahnón, P., 2017. Vanadium supersaturated Silicon system: a Theoretical and Experimental Approach. Journal of Physics D: Applied Physics.
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