High Efficiency Si/CdS Radial Nanowire Heterojunction Photodetectors Using Etched Si Nanowire Templates

p-Si/n-CdS radial heterojunction nanowires have been grown by pulse laser deposition of CdS on vertically aligned Si nanowires fabricated using a room temperature wafer-scale etching of p-type Si. Temperature-dependent photoluminescence characteristics have been studied in detail in the blue-green-red regions from these p-Si/n-CdS core-shell nanowires. The photocurrent spectra of the nanowire heterojunctions have been investigated at room temperature to study the spectral responsivity and detectivity of the core-shell nanowire diodes. The peak responsivity (1.37 A/W) and detectivity (4.39 X 10(11) cm Hz(1/2)/W) at -1 V show the potential of the nanoscaled devices for the high efficiency photodetectors in the visible-near-infrared spectrum.