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 × 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.