Nanostructured Silicon Sensors

Nanostructure porous silicon layers with systematically varied pore size of 8–70 nm were fabricated onto the p-type c-Si wafers using electrochemical anodizing method from HF + ethanol and HF + ethanol + CdCl 2 solutions (hereafter PS and PSCD, respectively). Gas and photo sensors based on c-Si/PS (or PSCD)/ CdS and c-Si/PS/Cd 0.4 Zn 0.6 O heterojunctions were synthesized by depositing CdS and Cd 0.4 Zn 0.6 O films onto the c-Si/PS (or PSCD) substrates by electrochemical deposition (ED hereafter). The morphology of the PS and PSCD layers, CdS, and Cd 0.4 Zn 0.6 O films was studied using scanning electron microscopy (SEM). Gas- and photosensitivity properties of heterojunctions were studied as a function of pore size. The optimal pore size is determined, which provides the maximum gas- and photosensitivity of heterojunctions in this study. It was established that the heterojunctions based on PSCD possess higher gas- and photosensitivity than heterojunctions based on PS.