Hybrid GaAsSb/GaAs Heterostructure Core–Shell Nanowire/Graphene and Photodetector Applications

Abstract

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.

Influence of the Underlying Substrate on the Physical Vapor Deposition of Zn-Phthalocyanine on Graphene

“…33 Although the experimental results clearly show a correlation between ZnPc growth, the type of substrate, and the number of graphene layers, SEM images of ZnPc deposited under two different flux regimes are not sufficient to decipher the fundamental mechanisms responsible for the morphology change. These mechanisms include a change in (i) structural defect in graphene, 47,48 (ii) surface energy, 49 (iii) mechanical strain, 50 and (iv) electrostatic doping 51 or even (v) a change in the substrate-induced polar field through graphene. 30 In order to identify the major factors responsible for ZnPc morphological change, Raman spectroscopy has been carried out on each graphene substrate (see Figure 6).…”

Vacancy designed 2D materials for electrodes in energy storage devices

“…The ballistic ejection of carbon atoms from graphene materials by irradiation has been reported and it was responsible for the abundance of point defects. [98][99][100] The synthesis of engineered defects in 2D graphene materials has been extensively studied. For example, Villarreal et al 101 have recently published research on defect formation in graphene materials due to the breaking of C-C bonds and development of C-substrate bonds by ultralow energy (15-40 eV) ion implantation (with He, Ne and Ar).…”

Heterostructure axial GaAsSb ensemble near-infrared p–i–n based axial configured nanowire photodetectors

“…Among various ternary III-V-V compound material systems, GaAsSb is attractive for the photodetector application due to their phase purity, higher carrier mobility, ease of bandgap engineering by simply varying the Sb composition, and most importantly, better understood Sb surfactant effect in engineering the NW growth kinetics and the NW properties [8][9][10][11][12]. Further, the bandgap of GaAsSb also encompasses the low loss near-infrared telecommunication wavelength range [8][9][10][11][12], with wide-ranging applications in light detection and ranging for the autonomous vehicle application and the optical interconnects in supercomputers. III-V p-i-n NWs are realized in both different configurations and different material systems.…”