THACH DINH SON THACH - Academia.edu (original) (raw)

Papers by THACH DINH SON THACH

We experimentally study the electromagnetic coupling between optical transitions in zinc oxide (Z... more We experimentally study the electromagnetic coupling between optical transitions in zinc oxide (ZnO) thin film and surface plasmons of graphene sheet. ZnO films are prepared by sol-gel method on Si substrate. Then graphene films, made by CVD method, are transferred onto ZnO films. Photoluminescence (PL) spectra, taken on both uncovered and covered positions, are compared to investigate the coupling between optical transitions of ZnO films and surface plasmons of graphene films. The existence of graphene layer on top of ZnO film leads to not only the suppression of PL peaks at high energies(from 2eV to 2.47eV), but also the enhancement of the PL peaks at lower energies (1.6eV and 1.8 eV). The enhancement and suppression of PL peaks of ZnO films depends on the annealing temperature of ZnO films. The higher the annealing temperature is, the stronger the effect becomes. The reason might be due the fact that films annealed at high temperature possess a rougher morphology and a stronger i...

fas.hcmut.edu.vn

Displacement measurement can be performed with high accuracy using phase-shifting method. In phas... more Displacement measurement can be performed with high accuracy using phase-shifting method. In phase-shifting method, it is often used four steps of phase-shifting for one cycle. In conventional method, to measure the displacement of an object by interferometer, the phase of reference beam should be shifted by every π/2 in four-step phase-shifting. Therefore, the error of this measurement is depended upon the phase-shifting angle. In this paper, we propose a new fabrication of Michelson interferometer. There are several changes in this fabrication to easily adjust the interferometer with a higher accuracy. This article show a simple interferometer with the reference of two light waves. These references are quite sensitive to the phaseshifting, each of them is different to the others when changing a very small phase (less than 1µm for visible light, with a very short time (T ≈ 2.10-15 s)). The important improvement of fabrication is using a piezoelectric actuator to prevent the vibration and to get the high accuracy in phase-shifting. Besides, the piezoelectric actuator also help us test the accuracy of the fabrication of Michelson interferometer.

Applied Mechanics and Materials, 2013

Temperature dependent photoluminescence (PL) properties of ZnO thin film prepared by sol-gel rout... more Temperature dependent photoluminescence (PL) properties of ZnO thin film prepared by sol-gel route were investigated. The excitonic-related emission peak at 3.336 eV dominates the spectra, and is attributed to the recombination of excitons bound to structural defects (DBX). Moreover, its thermal activation energy is 5.7 meV obtained by using least-squares fitting method. Compared to its larger localization energy, we propose that there exists a nonradiative relaxation path with energy released during the formation of DBX. The observed peak position of blue emission is in line with theoretical energy interval between the interstitial zinc level and valence band.

Zince Oxide (ZnO) and graphene have large potential in light emission device application as well ... more Zince Oxide (ZnO) and graphene have large potential in light emission device application as well as photoelectronic device. ZnO and graphene photoluminescence properties are still attracting many researchers to study. Understand mechanism of emission clearly, we can modify the photoluminescence properties for each application. In this paper, we report the mechanism of ZnO photoluminescence emission and the interaction between ZnO and Graphene in hybrid structure ZnO film/Graphene. First Graphene made by CVD method was transferred on to Silicon substrates. Then ZnO films were prepared by Hummer method. Samples were annealed at different temperature 250 o C, 350 o C, 500 o C respectively. Photoluminescence spectra at ZnO/Si site and Graphene/ZnO/Si site are compared to investigative the interaction between ZnO and graphene. Photoluminescence results show quenching effect and enhancement of ZnO photoluminescence. The reason may caused by the electromagnetic coupling between optical tra...

We experimentally study the electromagnetic coupling between optical transitions in zinc oxide (Z... more We experimentally study the electromagnetic coupling between optical transitions in zinc oxide (ZnO) thin film and surface plasmons of graphene sheet. ZnO films are prepared by sol-gel method on Si substrate. Then graphene films, made by CVD method, are transferred onto ZnO films. Photoluminescence (PL) spectra, taken on both uncovered and covered positions, are compared to investigate the coupling between optical transitions of ZnO films and surface plasmons of graphene films. The existence of graphene layer on top of ZnO film leads to not only the suppression of PL peaks at high energies(from 2eV to 2.47eV), but also the enhancement of the PL peaks at lower energies (1.6eV and 1.8 eV). The enhancement and suppression of PL peaks of ZnO films depends on the annealing temperature of ZnO films. The higher the annealing temperature is, the stronger the effect becomes. The reason might be due the fact that films annealed at high temperature possess a rougher morphology and a stronger i...

fas.hcmut.edu.vn

Displacement measurement can be performed with high accuracy using phase-shifting method. In phas... more Displacement measurement can be performed with high accuracy using phase-shifting method. In phase-shifting method, it is often used four steps of phase-shifting for one cycle. In conventional method, to measure the displacement of an object by interferometer, the phase of reference beam should be shifted by every π/2 in four-step phase-shifting. Therefore, the error of this measurement is depended upon the phase-shifting angle. In this paper, we propose a new fabrication of Michelson interferometer. There are several changes in this fabrication to easily adjust the interferometer with a higher accuracy. This article show a simple interferometer with the reference of two light waves. These references are quite sensitive to the phaseshifting, each of them is different to the others when changing a very small phase (less than 1µm for visible light, with a very short time (T ≈ 2.10-15 s)). The important improvement of fabrication is using a piezoelectric actuator to prevent the vibration and to get the high accuracy in phase-shifting. Besides, the piezoelectric actuator also help us test the accuracy of the fabrication of Michelson interferometer.

Applied Mechanics and Materials, 2013

Temperature dependent photoluminescence (PL) properties of ZnO thin film prepared by sol-gel rout... more Temperature dependent photoluminescence (PL) properties of ZnO thin film prepared by sol-gel route were investigated. The excitonic-related emission peak at 3.336 eV dominates the spectra, and is attributed to the recombination of excitons bound to structural defects (DBX). Moreover, its thermal activation energy is 5.7 meV obtained by using least-squares fitting method. Compared to its larger localization energy, we propose that there exists a nonradiative relaxation path with energy released during the formation of DBX. The observed peak position of blue emission is in line with theoretical energy interval between the interstitial zinc level and valence band.

Zince Oxide (ZnO) and graphene have large potential in light emission device application as well ... more Zince Oxide (ZnO) and graphene have large potential in light emission device application as well as photoelectronic device. ZnO and graphene photoluminescence properties are still attracting many researchers to study. Understand mechanism of emission clearly, we can modify the photoluminescence properties for each application. In this paper, we report the mechanism of ZnO photoluminescence emission and the interaction between ZnO and Graphene in hybrid structure ZnO film/Graphene. First Graphene made by CVD method was transferred on to Silicon substrates. Then ZnO films were prepared by Hummer method. Samples were annealed at different temperature 250 o C, 350 o C, 500 o C respectively. Photoluminescence spectra at ZnO/Si site and Graphene/ZnO/Si site are compared to investigative the interaction between ZnO and graphene. Photoluminescence results show quenching effect and enhancement of ZnO photoluminescence. The reason may caused by the electromagnetic coupling between optical tra...