We report on room temperature diode characteristics of ZnO:Al (AZO)/Si heterostructures by current-voltage measurements. In this study, with increasing AZO film thickness, systematic reduction in the turn-on potential (from 3.16 to 1.80 V) and the film stress are observed. Complementary capacitance-voltage studies reveal a decreasing trend in barrier height at the junction with increasing AZO film thickness. A gradual decrease in resistivity takes place with increasing AZO film thickness. Above observations are explained in the framework of AZO thickness dependent variation in grain size and in turn trap density at the grain boundaries influencing carrier transport across the adjacent grains. © 2013 © 2013 Author(s).

Aloke Kanjilal

Physics

(SoNS) School of Natural Sciences

Kumar M.

Som T.

Fulltext

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Shiv Nadar University

Effect of grain-boundaries on electrical properties of n-ZnO:Al/p-Si heterojunction diodes

AIP Advances

The efficacy of 50 keV Ar+-ion irradiation toward the interfacial and stoichiometric engineering of strained Al-doped ZnO (AZO)/TiO2 heterostructure is systematically investigated using a variety of experimental techniques, notably by cross-sectional transmission electron microscopy. Glancing-angle X-ray diffraction evidences the release of in-plane compressive stress from the as-grown AZO/TiO2 bilayer structure at a critical fluence of 1 × 1016 ions/cm2, and we discuss in the light of microcracks and voids formation combined with the dewetting phenomenon. Ion irradiation also leads to an improvement of stoichiometry in both top AZO and underneath amorphous TiO2 layers, as manifested by depth-dependent energy dispersive X-ray spectroscopy owing to the large diffusion of oxygen toward the AZO/TiO2 interfacial region through the AZO defect sites. Such ion beam induced self-healing in stoichiometry of AZO/TiO2 heterostructure has been attributed to a conjunction of sputtering and diffusion phenomena involving the constituent elements (Zn, Ti, and O). Further increase in ion fluence up to 5 × 1016 ions/cm2 causes a complete deterioration of the heterostructure with the formation of a graded layer via intermixing of these elements, followed by the evolution of voids. © 2018 Author(s).

Journal of Applied Physics

Probing the impact of energetic argon ions on the structural properties of ZnO:Al/TiO2 heterostructures

Al-doped ZnO (AZO) thin films of thicknesses 5,10, 15, 20, and 30nm were deposited on 500eV argon ion-beam fabricated nanoscale self-organized rippled-Si substrates at room temperature and are compared with similar films deposited on pristine-Si substrates (without ripples). It is observed that morphology of self-organized AZO films is driven by the underlying substrate morphology. For instance, for pristine-Si substrates, a granular morphology evolves for all AZO films. On the other hand, for rippled-Si substrates, morphologies having chain-like arrangement (anisotropic in nature) are observed up to a thickness of 20nm, while a granular morphology evolves (isotropic in nature) for 30nm-thick film. Photoluminescence studies reveal that excitonic peaks corresponding to 5-15nm-thick AZO films, grown on rippled-Si templates, show a blue shift of 8nm and 3nm, respectively, whereas the peak shift is negligible for 20-nm thick film (with respect to their pristine counter parts). The observed blue shifts are substantiated by diffuse reflectance study and attributed to quantum confinement effect, associated with the size of the AZO grains and their spatial arrangements driven by the anisotropic morphology of underlying rippled-Si templates. The present findings will be useful for making tunable AZO-based light-emitting devices. © 2015 AIP Publishing LLC.

Thickness-dependent blue shift in the excitonic peak of conformally grown ZnO:Al on ion-beam fabricated self-organized Si ripples

Chemically textured Si with improved absorption in the complete range of solar spectrum is investigated by ultraviolet/visible/near-infrared (UV/Vis/NIR) spectroscopy, showing an average specular reflectance of ∼0.4\% in the wavelength of 500-3000nm. The pyramidal structures on such solar-blind Si can reduce the reflectance further below 0.1\% in the UV region by conformal growth of granular Al-doped ZnO (AZO) films. X-ray diffraction analyses suggest the growth of polycrystalline AZO on faceted-Si. Moreover, marginal increase in electrical conductivity of AZO is found on textured surfaces, whereas rise in leakage current in Schottky-like Ag/AZO/Si/Ag heterostructure devices is noticed with increasing Si surface area. © 2014 AIP Publishing LLC.

Applied Physics Letters

Improved broadband antireflection in Schottky-like junction of conformal Al-doped ZnO layer on chemically textured Si surfaces

Journal of Alloys and Compounds

A novel ITO/AZO/SiO2/p-Si frame SIS heterojunction fabricated by magnetron sputtering

Physica B: Condensed Matter

Carrier transport and bandgap shift in n-type degenerate ZnO thin films: The effect of band edge nonparabolicity

Solar Energy Materials and Solar Cells

Sol–gel derived hydrogen annealed ZnO:Al films for silicon solar cell application

Advanced Materials

Silicon Filaments in Silicon Oxide for Next-Generation Photovoltaics

Interface-dependent rectifying TbMnO3-based heterojunctions