Tetrapod-Shaped CdSe Nanocrystals-Coated Multilayered Parallelepiped ZnO Structures-Based Dual-Wavelength Photodetector

Abstract

This letter reports a metal-semiconductor-metal (MSM) dual band photodetector (PD) realized by fabricating an interdigitated electrode structure of silver on tetrapod-shaped CdSe nanocrystals (NCs)-coated multilayered parallelepiped ZnO structure grown on a SiO2 grown silicon (Si) substrate. The proposed device exhibited a dual-wavelength detection property with room-temperature responsivities of 600 mA/W at 380 nm [i.e., ultraviolet (UV)] and 170 mA/W at 540 nm (i.e., visible) under ultralow-power illuminations condition of 20.07 and 25.2μ Wcm-2, respectively, at a low bias of 2 V. Under the same operating conditions, the detectivities at 380 and 540 nm were obtained as ~2.53 ×1011 Jones and ~7.267×1010 Jones, respectively. The analysis of the transient characteristics provided the rise time of 7.6 s and fall time of 6.7 s at 380 nm (UV), while the rise time of 0.72 s and fall time of 0.78 s were obtained at 540 nm (visible). © 1963-2012 IEEE.