Comparison of photoresponse characteristics between nitrogen and phosphorous doped n-C/p-Si heterostructure

Photoresponse of nitrogen and phosphorous doped n-C/p-Si heterostructure have been studied. Camphor (C₁₀H₁₆O) was used as starting precursor material in both cases. Phosphorous was doped in varying amounts (1%-7% by mass) and Nitrogen was doped in gas phase with varying partial pressure in the range from 0.3 to 50 mTorr. The doped carbon films were deposited on Silicon substrates by pulsed laser deposition (PLD) technique. Photoresponse of the films varied with increasing nitrogen and phosphorous content. Maximum photoresponse for phosphorous doped carbon films was observed for 5% doping and that for nitrogen doping was observed at 1 mTorr nitrogen partial pressure (NPP). Photoresponse was higher in case of nitrogen doping. Since nitrogen was doped in gas phase it has an advantage over phosphorous of having the better control as dopant. Photoresponse deteriorated in case of both phosphorous and nitrogen doping after the maximum overall photoresponse was observed. The total photoresponse variation was similar to carbon contributions for both cases. The contribution of silicon remained almost constant for P-doping. In case of NPP doping there is possible modification of the structure beyond 10 mTorr.