Piezo-phototronic Effect Enhanced UV/Visible Photodetector Based on Fully Wide Band Gap Type-II ZnO/ZnS Core/Shell Nanowire Array

Abstract

A high-performance broad band UV/visible photodetector has been successfully fabricated on a fully wide bandgap ZnO/ZnS type-II heterojunction core/shell nanowire array. The device can detect photons with energies significantly smaller (2.2 eV) than the band gap of ZnO (3.2 eV) and ZnS (3.7 eV), which is mainly attributed to spatially indirect type-II transition facilitated by the abrupt interface between the ZnO core and ZnS shell. The performance of the device was further enhanced through the piezo-phototronic effect induced lowering of the barrier height to allow charge carrier transport across the ZnO/ZnS interface, resulting in three orders of relative responsivity change measured at three different excitation wavelengths (385, 465, and 520 nm). This work demonstrates a prototype UV/visible photodetector based on the truly wide band gap semiconducting 3D core/shell nanowire array with enhanced performance through the piezo-phototronic effect.

Heterojunctions Based on II-VI Compound Semiconductor One-Dimensional Nanostructures and Their Optoelectronic Applications

“…The EDS line scan across the nanowire clearly demonstrated a characteristic core-shell elemental distribution, further confirming the successful synthesis of a CdSe/ZnTe core-shell nanowire array with an abrupt, nearly lattice-matched interface. Wang et al constructed a fully wide band gap ZnO/ZnS type-II heterojunction core-shell nanowire array for high-performance broad UV/VIS photo-detecting [35]. ZnO nanowire array was first synthesized on ITO substrates and a ZnS shell layer was deposited by the PLD method.…”

Photoelectric characteristics of the p–n junction between ZnO nanorods and polyaniline nanowires and their application as a UV photodetector

“…It shows that electrical conductivity of the ZnO and ZnO/PANI device would be enhanced when they were irradiated with UV light. The reason was that the electrons of ZnO were excited from valence band (VB) to the conduction band (CB) to become the free exciton when it was illuminated with UV light [9]. Furthermore, the electrical conductivity of ZnO/PANI device could be enhanced much more than ZnO device when they were irradiated with same UV.…”

“…With a wide direct band gap of 3.37 eV and a large 2 exciton binding energy of 60 meV, ZnO nanostructure has been widely investigated and exhibited potential applications for UV photodetectors [5][6][7][8]. The photodetectors with various types and shapes of ZnO have been investigated by many research groups [9][10][11][12][13]. However, the UV detector based on pure ZnO suffers from the weak responsivity which will restrict the application of the device.…”

Hybrid Structures of ITO-Nanowire-Embedded ITO Film for the Enhanced Si Photodetectors

“…In addition, high-performing UV photodetectors have specific applications in ozone sensing, flame detection, and military surveillance [5,6]. To improve the performance of a UV photodetector, various designs and materials have been applied, such as the GaN-based Schottky junction [6], graphene-based junction [6][7][8], GaAs/AlGaAs nanowires [9], ITO nanodomes [10], ITO nanowires with ZnO film [11,12], NiO/ZnO films [5], ZnO/ZnS nanowires [13], ZnO nanorods [14], ZGO nanowires [15], and Si/ZnO nanowires [1]. When considering the complexity of elaborate photodetector designs, the fabrication steps and cost should also be considered for practical applications [2].…”