Optical and dielectric properties of ZnO tetrapod structures at terahertz frequencies

Han, Jiaguang; Zhang, Zhu; Ray, Sanith; Azad, Abul K.; Zhang, Weili; He, Ming; Li, Shihong; Zhao, Yiping

doi:10.1063/1.2222329

Cited by 61 publications

(43 citation statements)

References 25 publications

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“…On the other hand, SCP process also contributes to the enhanced dielectric response. It is known that interface density of the nanostructures is much more than that of bulks, and lots of defects such as dislocations, dangling bonds and microporosities exist in the interfaces [13][14][15]30]. Then, the space charges in the nanowires will move towards the opposite poles of the electric when exposed to the external electric field.…”

Section: Resultsmentioning

confidence: 99%

“…Compared with these optoelectronic properties, the dielectric behaviors of SnO 2 nanowires are poorly known. It is well known that the enhanced dielectric behaviors can be observed in some metal oxide nanostructures such as Al 2 O 3 nanobelts [13], ZnO tetrapods [14], MgO nanoflowers [15] and SnO 2 nanoparticles [16,17] because of a great space charge polarization (SCP) process. As for n-type SnO 2 , O vacancies as native defects can influence the optical and electrical properties of the nanowires.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, photoluminescence and dielectric properties of O-deficient SnO2 nanowires

Guo

Wang

et al. 2009

Journal of Alloys and Compounds

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis, photoluminescence and dielectric properties of O-deficient SnO2 nanowires

Guo

Wang

et al. 2009

Journal of Alloys and Compounds

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“…For the refractive indices near 2 THz, we use the experimentally determined values of 3.8 and 2.8 for GaAs and ZnO, respectively. 65,66 Furthermore, from previously reported measurements with GaAs THz-QC-laser waveguides based on surface plasmons 5,8 we take a=CN p ¼ 20 cm À1 for both structures considered here.…”

Section: Simulation Resultsmentioning

confidence: 99%

Numerical Simulation of ZnO-Based Terahertz Quantum Cascade Lasers

Bellotti

Paiella

2010

Journal of Elec Materi

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In this work, a particle-based Monte Carlo model is used to quantify the potential of terahertz sources based on the ZnO-based material system relative to existing devices based on GaAs/AlGaAs quantum wells. Specifically, two otherwise identical quantum cascade structures based on ZnO/ MgZnO and GaAs/AlGaAs quantum wells are designed, and their nonequilibrium carrier distributions are then computed as a function of temperature. The simulation results show that, because of their larger optical phonon energy, ZnO/MgZnO quantum cascade laser structures exhibit weaker temperature dependence of the population inversion than in the case of similar structures made of GaAs/AlGaAs. In particular, as the temperature is increased from 10 K to 300 K, population inversion is found to decrease by a factor of 4.48 and 1.50 for the AlGaAs and MgZnO structure, respectively. Based on these results, the MgZnO devices are then predicted to be, in principle, capable of laser action without cryogenic cooling.

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“…THz, experimentally obtained power absorption and refractive index for single crystal ZnO are fitted quite accurately and compared with ZnO nanowire's results [19][20][21] . Unlike other ZnO nanomaterials, such as nanowires, tetrapods and prismlike structures, the annealed ZnO nanoparticles show a strong absorption at higher frequencies starting from 0.9 THz.…”

mentioning

confidence: 87%

Study of optical and dielectric properties of annealed ZnO nanoparticles in the terahertz regime

Wang

Woo

Tian

et al. 2009

Optoelectron. Lett.

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The frequency-dependent optical and dielectric properties of annealed ZnO nanoparticles in the range of 0.1 to 0.9 THz are studied by using terahertz time-domain spectroscopy (THz-TDS). The refractive index, power absorption and complex dielectric constants are obtained and the experimental results are well fit with a simple effective medium theory in conjunction with a pseudo-harmonic model. This study reveals that annealed ZnO nanoparticles exhibit the similar phonon response characteristics to the single ZnO crystal and other ZnO nanostructures, such as tetrapods and nanowires.In recent years, ZnO has attracted great research interest because of its unique properties and a variety of potential applications in electro-optic, acousto-optic, optoelectronic devices, chemical sensors and piezoelectrics [1][2][3] . ZnO can be a highly potential choice for ultraviolet light emitters and low voltage applications [4,5] , and it also could be used in integrated active optic devices and generation of high power terahertz pulses [6] . Some ZnO nanoparticles have shown exciting applications in the field of optoelectronics due to its unique capability of being integrated into nano-devices with very low power consumption [7] . Recent advancement in nanomaterial research has revealed that a new type of ZnOorganic coated nanoparticles has luminescence properties [8] .In this paper, we present a study of far-infrared optical and dielectric properties of annealed ZnO nanoparticles made from the luminescence coated ZnO nanopowders in the regime of 0.1-0.9 THz using the terahertz time-domain spectroscopy system (THz-TDS).The THz-TDS system is a photoconductive switch-based spectrometer with four parabolic mirrors arranged in an 8-F confocal geometry [9] . This confocal configuration enables excellent beam coupling between the transmitter and the receiver. A frequency-independent 3.5 mm-diameter terahertz beam waist is achieved for sample characterization. The THz-TDS system is optically excited using a Kerr-lens modelocked Ti:sapphire laser of 26 fs pulse width and 88 MHz repetition rate and has an useful bandwidth of 0.1-4.5 THz (3 mm-67 m) and a signal-to-noise ratio (S/N) greater than 1.0 10 4 :1.The annealed ZnO nanopowder is prepared in the following two steps. First, wet chemistry method called reverse micelle technique is used to make the luminescence coated ZnO nanopowders [10] . The zinc acetylacetonate hydrate powder (1.4122 gm, 5.36 mmole) is dissolved in 35 ml ethanol and put into a flask that is connected with a water condenser. 1 ml DI water and stabilizer polyethylene glycol biscarboxymethyl ether (0.85 gm, 3.3 mmole) is then mixed with the prepared murky solution. The murky solution is then heated up to boiling point under vigorous magnetic stirring. Another cooled solution is prepared using sodium hydroxide pellets (0.4 gm, 10 mmole) which is dissolved in 35 ml ethanol. The cooled solution with temperature around 0 o C is then added slowly using a transfer pipet into the boiling solution. After that, a white preci...

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Optical and dielectric properties of ZnO tetrapod structures at terahertz frequencies

Cited by 61 publications

References 25 publications

Synthesis, photoluminescence and dielectric properties of O-deficient SnO2 nanowires

Synthesis, photoluminescence and dielectric properties of O-deficient SnO2 nanowires

Numerical Simulation of ZnO-Based Terahertz Quantum Cascade Lasers

Study of optical and dielectric properties of annealed ZnO nanoparticles in the terahertz regime

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