Hydrothermal growth and characterization of ZnO single crystals of high purity

Sakagami, Noboru

doi:10.1016/s0022-0248(08)80050-4

Cited by 29 publications

(13 citation statements)

References 9 publications

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“…It has been reported that the oxygen-rich conditions obtained by using H 2 O 2 in an alkali solvent are favorable for decreasing the oxygen atomic vacancies and for growing ZnO single crystals of high purity. [22] This novel growth route, which combined a hydrothermal oxidative method and solvent-evaporation technique, efficiently enhanced the reaction and growth conditions and, therefore, speedily grew well-crystallized bulk ZnO single crystals. The main technique was to modify the release of solution vapor, thereby controlling the crystal nucleation and consequent growth process.…”

Section: Growth Processmentioning

confidence: 99%

Growth of Bulk ZnO Single Crystals via a Novel Hydrothermal Oxidative Pressure‐Relief Route

Zheng

Guo²,

Qian

2005

Adv Funct Materials

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A novel hydrothermal oxidative pressure‐relief (HOPR) route has been successfully developed for the growth of high‐quality bulk ZnO single crystals, using metallic zinc and H2O2 as the raw materials, at 400 °C for 20 h in an alkali solvent. X‐ray powder diffraction reveals the ZnO crystals have a wurtzite structure. Two typical morphologies of perfect hexagonal pyramidal and hexagonal prismatic ZnO single crystals, and bidirectional adhesive crystals, are identified by scanning electron microscopy analysis. The average size of the single crystals is ∼ 1.0 mm in length and ∼ 0.2 mm in diameter. Short hexagonal prismatic, novel polygonal layer‐like, and nanowire ZnO crystals are also obtained by altering the reaction conditions, such as the reaction time and the speed of pressure release. The growth mechanism is a spontaneous nucleation and self‐growth process. This novel HOPR route gives an alternative choice for obtaining well‐crystallized ZnO bulk crystals from solution.

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Section: Growth Processmentioning

confidence: 99%

Growth of Bulk ZnO Single Crystals via a Novel Hydrothermal Oxidative Pressure‐Relief Route

Zheng

Guo²,

Qian

2005

Adv Funct Materials

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“…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%

Effect of complexing agent on hydrothermal growth of ZnO crystals

DiLeo

Romano

Schaeffer

et al. 2004

Journal of Crystal Growth

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“…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.…”

mentioning

confidence: 96%

“…The growth direction dependence of impurity concentration was found the reason for the anisotropy in optical properties [31]. The concentration of the excess Zn atoms in ZnO was determined from 0.8 to 1.7 ppm [4]. This value was at the level or lower the level of the concentration of most metallic impurities.…”

mentioning

confidence: 96%

“…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].…”

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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 of high purity

Cited by 29 publications

References 9 publications

Growth of Bulk ZnO Single Crystals via a Novel Hydrothermal Oxidative Pressure‐Relief Route

Growth of Bulk ZnO Single Crystals via a Novel Hydrothermal Oxidative Pressure‐Relief Route

Effect of complexing agent on hydrothermal growth of ZnO crystals

Atomic absorption photometry of excess Zn in ZnO

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