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Effect of EU doping on the optical properties of ZnO nanorods prepared by chemical bath deposition
Yatskiv, Roman ; Bašinová, Nikola ; Grym, Jan ; Vaniš, Jan
We report on the properties of Eu-doped ZnO nanorods prepared by chemical bath deposition from aqueous solutions in an autoclave. The autoclave enables to grow the nanorods above the boiling point of water. The nanorods were characterized by scanning electron microscopy, secondary ion mass spectroscopy, and low temperature photoluminescence spectroscopy. Under the UV light excitation, the nanorods show a strong blue emission at 450 nm, which is associated with the 4f(6)5d - 4f(4) transitions of Eu2+ ions. We discuss the mechanisms responsible for the blue luminescence. We further clarify how the growth parameters affect the morphology and the optical properties of the nanorods. Growth temperatures above the boiling point of water significantly influence the intensity ratio of the near band edge emission to the deep level emission and greatly enhance optical quality of the nanorods.
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Optoelectrical characterization of well oriented n-type zno nanorod arrays on p-type GaN templates
Yatskiv, Roman ; Grym, Jan ; Schenk, Antonín ; Vaniš, Jan ; Roesel, David ; Chlupová, Šárka
A heterojunction formed between a single n-type ZnO nanorod and p-type GaN template was successfully prepared by low cost chemical bath deposition technique. Periodic circular patterns were fabricated by focused ion beam etching through poly(methyl methacrylate) mask to control the size, position, and periodicity of the ZnO nanorods. A possible growth mechanism is introduced to explain the growth process of the nanorods. Optical and electrical properties of the heterojunctions were investigated by low temperature photoluminescence spectroscopy and by the measurement of current-voltage (I-V) characteristics. The I-V characteristics were measured by directly contacting single ZnO nanorods with the conductive atomic force microscopy tip. The diode-like rectifying behavior was observed with a turn-on voltage of 2.3 V and the reverse breakdown voltage was 5 V
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Electrical properties of nanoscale heterojunctions formed between GaN and ZnO nanorods
Tiagulskyi, Stanislav ; Yatskiv, Roman ; Grym, Jan ; Schenk, Antonín ; Roesel, David ; Vaniš, Jan ; Hamplová, Marie
Vertical periodic arrays of ZnO nanorods are prepared by hydrothermal growth on GaN templates patterned by focused ion beam. Electro-physical properties of a single vertically-oriented ZnO nanorod are investigated by measuring the current-voltage characteristics using a nanoprobe in a scanning electron microscope. This technique enables to observe the surface morphology of ZnO nanorods simultaneously with their electrical characterization in vacuum. The vacuum chamber rejects the impact of gas adsorption and light irradiation, which both affect the properties of ZnO nanorods. Moreover, mechanical damage and strain induced during the nanorod transfer are eliminated. Nonlinear current-voltage characteristics under the forward bias are explained by the tunneling-recombination process and by the space charge limited current. The high reverse bias current in the p-n heterojunction is attributed to direct tunneling via a narrow tunnel barrier
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