This work reports a comprehensive investigation of the effect of gallium telluride (GaTe) cell temperature variation (TGaTe) on the morphological, optical, and electrical properties of doped-GaAsSb nanowires (NWs) grown by Ga-assisted molecular beam epitaxy (MBE). These studies led to an optimum doping temperature of 550 °C for the growth of tellurium (Te)-doped GaAsSb NWs with the best optoelectronic and structural properties. Te incorporation resulted in a decrease in the aspect ratio of the NWs causing an increase in the Raman longitudinal optical/transverse optical vibrational mode intensity ratio, large photoluminescence emission with an exponential decay tail on the high energy side, promoting tunnel-assisted current conduction in ensemble NWs and significant photocurrent enhancement in the single nanowire. A Schottky barrier photodetector (PD) using Te-doped ensemble NWs with broad spectral range and a longer wavelength cutoff at ∼1.2 µm was demonstrated. These PDs exhibited responsivity in the range of 580–620 A W−1 and detectivity of 1.2–3.8 × 1012 Jones. The doped GaAsSb NWs have the potential for further improvement, paving the path for high-performance near-infrared (NIR) photodetection applications.

We report the first study on doping assessment in Te-doped GaAsSb nanowires (NWs) with variation in Gallium Telluride (GaTe) cell temperature, using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), conductive-atomic force microscopy (C-AFM), and scanning Kelvin probe microscopy (SKPM). The NWs were grown using Ga-assisted molecular beam epitaxy with a GaTe captive source as the dopant cell. Te-incorporation in the NWs was associated with a positive shift in the binding energy of the 3d shells of the core constituent elements in doped NWs in the XPS spectra, a lowering of the work function in doped NWs relative to undoped ones from UPS spectra, a significantly higher photoresponse in C-AFM and an increase in surface potential of doped NWs observed in SKPM relative to undoped ones. The carrier concentration of Te-doped GaAsSb NWs determined from UPS spectra are found to be consistent with the values obtained from simulated I–V characteristics. Thus, these surface analytical tools, XPS/UPS and C-AFM/SKPM, that do not require any sample preparation are found to be powerful characterization techniques to analyze the dopant incorporation and carrier density in homogeneously doped NWs.

Band gap engineering of GaAsSbN nanowires (NWs) grown by Ga-assisted molecular beam epitaxy and demonstration of a Te-doped axial GaAsSbN NW-based Schottky barrier photodetector on p-Si (111) in the near-infrared region are reported. Stringent control on NW nucleation conditions, stem growth duration, and NW exposure to the N-plasma were found to be critical for the successful growth of high-quality dilute nitride quaternary GaAsSbN NWs in the axial configuration. Planar defect-free structures were realized with room temperature photoluminescence (PL) characteristics, revealing reduced N-induced point defects and nonradiative recombination centers. N incorporation in the dilute nitride NWs was ascertained from PL and Raman spectral mode shifts and shapes and weak temperature-dependent PL peak energy. The advantage of Te-doping in dilute nitride NWs using a GaTe captive source is the compensation of point defects, as evidenced by a significant improvement in PL characteristics, Raman mode shifts, and spectral shape, with improved photodetector device performance relative to intrinsic dilute nitride NWs. Te-doped GaAsSbN NW Schottky-based photodetectors have been demonstrated on both single and ensemble configurations with a resultant responsivity of 5 A/W at 860 nm and 3800 A/W at 1100, respectively. Detectivity of 3.2 × 10 10 Jones was achieved on the Te-doped ensemble NW device. The findings presented in this work showcase prospects for rich band gap engineering using doped GaAsSbN NWs for near-infrared region device applications.

We report the growth of vertical, high-quality GaAs0.9Sb0.1 nanowires (NWs) with improved density on oxygen (O2) plasma-treated monolayer graphene/SiO2/p-Si­(111) by self-catalyzed molecular beam epitaxy. An O2 plasma treatment of the graphene under mild conditions enabled modification of the surface functionalization and improved reactivity of the graphene surface to semiconductor adatoms. The rise in the disorder peak of the Raman mode, decreased surface conductivity, and creation of additional O2 groups of plasma-treated graphene compared to that of pristine graphene confirmed functionalization of the graphene. To enhance the nucleation centers further for the vertical yield of NWs on the graphene surface, NWs were grown on a higher Sb composition GaAs0.6Sb0.4 stem for surface engineering the graphene surface via the surfactant effect of Sb and for better lattice matching. The NWs grown under optimal conditions exhibited a zinc blende crystal structure with no discernible structural defects. The NWs with a GaAs-passivated shell exhibited photoluminescence emission at 1.35 eV at 4 K and 1.28 eV at room temperature. The ensemble device fabricated with a top segment of GaAsSb NW-doped n-type using a GaTe captive source exhibited an optical responsivity of 110 A/W with a detectivity of 1.1 × 1014 Jones. These results of hybrid GaAsSb NW heterostructure/graphene devices show significant potential toward the fabrication of flexible near-infrared photodetector device applications. Further, the simple and efficient O2 plasma treatment approach for surface engineering of graphene in conjunction with a high Sb compositional stem has shown to be a promising route that can be broadly applicable for the growth of other III–V ternary material systems for improving the vertical yield of NWs.

In this study, molecular beam epitaxially grown axially configured ensemble GaAsSb/GaAs separate absorption, charge, and multiplication (SACM) region-based nanowire avalanche photodetector device on non-patterned Si substrate is presented.