Hydrothermal Growth and Characterization of ZnO Single Crystals

Sakagami, Noboru; Shibayama, Kimio

doi:10.7567/jjaps.20s4.201

Cited by 15 publications

(15 citation statements)

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“…The oxygen pressure used during the growth process for the epilayers is 10 −5 torr (sample A), 10 −4 torr (B) and 10 −3 torr (C), which tunes the carrier concentration. Sample D (commercial single crystal from Tokyo-Denpa Company Ltd. grown by hydrothermal method 12 ) is mounted on fused silica and polished down to a few microns for transmission measurements.…”

mentioning

confidence: 99%

Room-temperature spin coherence in ZnO

Ghosh

Sih

Lau

et al. 2005

Applied Physics Letters

126

102

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Time-resolved optical techniques are used to explore electron spin dynamics in bulk and epilayer samples of n-type ZnO as a function of temperature and magnetic field. The bulk sample yields a spin coherence time T * 2 of 20 ns at T = 30 K. Epilayer samples, grown by pulsed laser deposition, show a maximum T * 2 of 2 ns at T = 10 K, with spin precession persisting up to T = 280 K.A lot of attention has been focused on zinc oxide (ZnO) because of material properties that make it well-suited for applications in ultra-violet light emitters, transparent high-power electronics and piezoelectric transducers. In addition, the theoretical work of Dietl et al ., 1 predicting room temperature ferromagnetism for Mn-doped p-type ZnO, has revealed the possibility that ZnO may be an appropriate candidate for spintronics. 2 The magnetic properties of thin films of ZnO with transition ion doping, 3,4,5 are being widely investigated, but practical spintronics applications would also require long spin coherence time and spin coherence length.

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confidence: 99%

Room-temperature spin coherence in ZnO

Ghosh

Sih

Lau

et al. 2005

Applied Physics Letters

126

102

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“…Zinc acetate dihydrate (98%, Aldrich) was dissolved in about 50 g of deionized, degassed water. A series of syntheses were done with only hydroxide as a ligand, for zinc molalities ranging from 0.038 to 0.061, pH 14 and at least 4 molar equivalents of KOH (85+%, Aldrich) added to each pretreated sample to enable formation of Zn(OH) 4 2À . To all other solutions, one molar equivalent of one of the following reagents was added: ethylenediaminetetraacetic acid (99.5%, Aldrich), ethylenediaminetetraacetic acid disodium salt dihydrate (99+%, Aldrich), diethylenetriaminepentaacetic acid (DTPA) (97%, Aldrich) and tetraethylenepentamine pentahydrochloride (98%, Aldrich).…”

Section: Methodsmentioning

confidence: 99%

“…Currently, hydrothermal synthesis of crystals requires the addition of lithium hydroxide as a mineralizer, which compromises the electrical properties of the product [3,4]. Thus, the prospect of synthesizing high-quality crystals without the need for lithium is worth pursuing.…”

Section: Introductionmentioning

confidence: 99%

“…Large, pure crystals of technological materials such as a-quartz (SiO 2 ) [2], a-corundum (Al 2 O 3 ) [2], KTP (KTiOPO 4 ) [1] and zincite (ZnO) [3][4][5] have been grown with the hydrothermal method. In this synthetic regime, slow diffusion rates are less of a hindrance to crystal growth because of a significant decrease in water viscosity.…”

Section: Introductionmentioning

confidence: 99%

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Effect of complexing agent on hydrothermal growth of ZnO crystals

DiLeo

Romano

Schaeffer

et al. 2004

Journal of Crystal Growth

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“…This value was at the level or lower the level of the concentration of most metallic impurities. A nonstoichiometry in the grown ZnO is enhanced due to a reductive atmosphere under hydrothermal conditions [32]. The dependence of defect formation on the annealing in O 2 and N 2 atmospheres showed that below 850 0 C, Zn interstitials become the dominated point defects but for the ZnO films annealed at higher temperatures, oxygen vacancies become the predominant defects [33].…”

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confidence: 99%

Atomic absorption photometry of excess Zn in ZnO

Lott

Shinkarenko

Kirsanova

et al. 2005

phys. stat. sol. (c)

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PACS 61.50. Nw, 61.72.Ji, 64.70.Hz Zn excess in ZnO is built up automatically at high temperatures. Excess Zn in hydrothermally grown ZnO single crystals were investigated by the atomic absorption photometry (AAP) method. To determine the excess zinc in ZnO samples, the AAP of zinc vapour was used in the conditions of solid-vapour equilibrium. Zn AAP allowes to eliminate excess Zn connected differentially in ZnO samples. To fix Zn non-stoichiometry, all the ZnO samples tested were previously heat treated at temperature interval from 850 to 900 0 C and at fixed Zn vapour pressures from 0.1 to 0.9 of saturated zinc vapour pressure at given treatment temperature. The analysis of temperature dependence of zinc vapour pressure indicated that the impurity metals take active role in the determination of non-stoichiometric zinc. The impurities Mn, Fe, Co, Ni and Cu form oxides which will reduce during annealing in Zn vapor up to metals form. During AAP measurement in optical cuvette, these metals react with ZnO and give additional Zn vapor pressure.1 Overview ZnO is used in a wide range of scientific and technological applications, such as optoelectronic devices, varistors, devices for surface acoustic waves and planar optical waveguides, transparent electrodes and transparent windows for a solar cell, gas sensors, flat panel diplays, catalysts, ferroelectric memories and spintronic devices, antibacterial agent and ZnO can satisfy the commercial desire for blue and ultraviolet light emitting devices -it is suitable to grow the high quality ZnO homoepilayer on the ZnO substrate [1][2][3]. For that reason, it is important to produce high quality ZnO bulk crystals for substrates of ZnO-related devices. The hydrothermal method has an advantage to grow large bulk crystals due to the growth under low supersaturation [4][5][6]. Some doubts were raised about the quality of such crystals because they have often exhibited large X-ray rocking curve widths and low photoluminescence yield with large linewidths [7]. But if the surface damage due to mechanical polishing was overcome, hydrothermal ZnO crystals provided a competitive substrate for homoepitaxial growth [7,8]. As the hydrothermal crystals invitably involve alkali metals from solution and small amounts of metallic impurities then one of the problems in hydrothermally grown ZnO crystals is the contamination of the crystal with metallic impurities. The concentration of impurities exceeds often the concentration of intrinsic defects. The colourless crystals were found with a total impurity content of less than 1 ppm [4,9] but it is found that the green colouration of the hyrothermally grown crystals may be due to the presence of iron in concentration up to 60 ppm [9]. The solubilities of metal oxides in ZnO are high. For example the solubility of Fe in ZnO is 7 mole% at 800 0 C [10]. Fe in ZnO appears as a result of the corrosion of the inner wall of the autoclave [11]. The thermal treatment of ZnO crystal results in the formation of associates between metal impurities [12,...

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Hydrothermal Growth and Characterization of ZnO Single Crystals

Cited by 15 publications

References 0 publications

Room-temperature spin coherence in ZnO

Room-temperature spin coherence in ZnO

Effect of complexing agent on hydrothermal growth of ZnO crystals

Atomic absorption photometry of excess Zn in ZnO

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