Ultraviolet Photodetector Based on GaN/AlN Quantum Disks in a Single Nanowire

Abstract

We report the demonstration of single-nanowire photodetectors relying on carrier generation in GaN/AlN QDiscs. Two nanowire samples containing QDiscs of different thicknesses are analyzed and compared to a reference binary n-i-n GaN nanowire sample. The responsivity of a single wire QDisc detector is as high as 2 x 10(3) A/W at lambda = 300 nm at room temperature. We show that the insertion of an axial heterostructure drastically reduces the dark current with respect to the binary nanowires and enhances the photosensitivity factor (i.e., the ratio between the photocurrent and the dark current) up to 5 x 10(2) for an incoming light intensity of 5 mW/cm(2). Photocurrent spectroscopy allows identification of the spectral contribution related to carriers generated within large QDiscs, which lies below the GaN band gap due to the quantum confined Stark effect.

Double strain state in a single GaN/AlN nanowire: Probing the core-shell effect by ultraviolet resonant Raman scattering

“…2 Ultra-violet photodetectors based on a single GaN NW containing quantum discs have also been reported. 3 New possibilities for wavelength tuning have been offered with the demonstration of GaN NW-ring lasers. 4 The unique geometry and properties of semiconductor NWs have motivated their use for new applications, such as nanoscale photodetectors with high polarization degree of detection.…”

UV Photosensing Characteristics of Nanowire-Based GaN/AlN Superlattices

“…14 In comparison with planar devices, almost defect-free semiconductor nanowires open the possibility of exploiting the photoconductive gain while avoiding the deleterious effects of grain boundaries and dislocations on the spectral response. 18 Both ZnO and (Al,Ga)N are promising choices to be used as miniature, visible-blind, ultraviolet (UV) photosensors, [11][12][13][14]16,19 but GaN presents advantages in terms of physical and chemical robustness as well as for controlled doping.…”

Three-dimensional nanoscale study of Al segregation and quantum dot formation in GaAs/AlGaAs core-shell nanowires

“…[15][16][17][18] Nanowires, furthermore, represent a model system for atom probe analysis, 19-24 as they closely approximate the shape of a field-emission tip. Nevertheless, and despite the interest of nanowire-based QDs for quantum information [25][26][27][28][29] and for their integration in nanoscale optoelectronic devices, [30][31][32][33] no studies of nanowire QDs by APT have been reported yet.Core-shell GaAs/AlGaAs nanowires grown by molecular beam epitaxy (MBE) have been shown to exhibit narrow luminescence and single photon emission, ascribed to QDs forming occasionally at the external corners of the AlGaAs shells. 27 Isolated emissions centered around 670 nm ($1.85 eV) could be found by cathodoluminescence (CL) spectroscopy, with a typical mean frequency along the axis of the order of one spot per micron.…”