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Abstract: An experimental study of the optical properties of PVA coated In2O3 nanoparticles was performed with characterization methods including photoluminescence, absorption and point source, photogenerated current–voltage measurements. The photoluminescence results show that PVA can suppress the parasitic green emission by modifying defect energy states introduced by oxygen vacancies. Thin films fabricated from PVA coated In2O3 nanoparticles show higher photocurrent and suppressed dark current, which may be promising for UV photodetector applications. [Copyright &y& Elsevier]

Abstract: A near ultraviolet (UV) photodetector is fabricated from colloidal In2O3 nanoparticles coated with polyvinyl-alcohol (PVA). The device exhibits lower dark current and higher responsivity compared with a photodetector fabricated from uncoated In2O3 nanoparticles. The rise and fall time of the PVA coated photodetector is about 500s and 1600s, respectively, one half of the uncoated device. The faster response time of the PVA enhanced photodetector is due to surface passivation which reduces the surface defects while enhancing desorption of oxygen from the nanoparticle surface, thus increasing free carrier concentration. [Copyright &y& Elsevier]

Enhanced near band gap edge (NBE) emissions of PVA–ZnOnanoparticleswere achieved by employing SiO2–Au core/shell nanostructureswhereas the defect-level emission (DLE) is greatly suppressed. A maximumenhancement of nearly 400% was observed using SiO2–Aufor the emission with optical resonance at 554 nm. SiO2–Au core/shell nanostructures also show a superior tunabilityof resonance energy as compared to that of the pure metal nanoparticles.The enhancement of the NBE emission and suppressed DLE is ascribedto the transfer of the energetic electrons excited by surface plasmonfrom metal nanoparticles to the conduction band of ZnO nanoparticles. [ABSTRACT FROM AUTHOR]

An ultraviolet heterojunction photodiode consisting of epitaxially grown p-GaN layers and polyvinyl alcohol coated ZnO colloidal nanoparticles exhibits a lowpass and bandpass alternative property depending on the illumination direction. At 0 V bias, a time response on the order of 10 s of milliseconds was demonstrated with a responsivity on the order of mA/W with about 100 nW of ultraviolet illumination. The rectification ratio at ±5 V was 1000 under dark environment. Deposition of colloidal ZnO nanoparticles on an independent p-GaN substrate introduces a technique to create a heterostructure pn junction photodiode with wavelength selection by back illumination. [ABSTRACT FROM AUTHOR]