Issues in ZnO homoepitaxy

Cho, M.W.; Harada, Chihiro; Suzuki, Hiroshi; Minegishi, Tsutomu; Yao, Takafumi; Ko, Hang-Ju; Maeda, Katsumi; Nikura, I.

doi:10.1016/j.spmi.2005.08.022

Cited by 50 publications

(51 citation statements)

References 8 publications

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“…One observes a significant change in the spectra obtained at low voltage with respect to the high-voltage spectra, and significant differences are observed between the samples with changes in the relative intensities of the different peaks, accounting for depth distributions of the defects responsible for the different bands. The AFRL sample shows a very low CL intensity for low-voltage acceleration beam, which evidences a severely damaged surface with very strong nonradiative recombination; for increasing acceleration voltage, the luminescence is enhanced, specially the visible band, which is progressively enhanced up to a depth around 3-4 mm, which should correspond to the region disturbed by polishing and surface chemisorption, in agreement with other reports [4]. One observes a very weak luminescence emission for AFRL sample at low kV, as compared with TD sample, which is due to the better surface preparation of TD sample; the AFRL sample should have a disordered layer close to the surface, around 0.5 mm thick, which is minimized in TD sample.…”

Section: Resultssupporting

confidence: 91%

“…Plates cut from the oxygen polar face of the seed (c À sector) present a much higher concentration of impurities (E5 Â À10 Â ), which makes them not suitable for UV device applications. TD sample was not analyzed by SIMS, though this material is known to present much lower impurity concentrations, around one order of magnitude below [4,5].…”

Section: Experimental Setup and Samplesmentioning

confidence: 99%

“…The result of these phenomena is that the substrate is severely disturbed up to a depth of a few mm [4,8]. A recent work by Cho et al [4] established a disturbed depth above 4 mm. Accordingly, the properties of the ZnO substrates for homoepitaxial growth should be determined by the defects proper to the growth process, and the defects induced by polishing and the chemical reactivity of the surface.…”

Section: Introductionmentioning

confidence: 98%

“…The high-quality ZnO wafers are expected to boost the progress of commercial ZnO-based devices. However, ZnO wafers machined from ZnO crystals are not yet satisfactory for homoepitaxial growth [4]; therefore, other alternative substrates, mainly sapphire, are still preferred. Nevertheless, the achievement of highquality ZnO wafers is necessary for the breakthrough of high-power ZnO-based devices.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the ZnO surfaces are very reactive, oxygen chemisorption being also a relevant issue [7]. The result of these phenomena is that the substrate is severely disturbed up to a depth of a few mm [4,8]. A recent work by Cho et al [4] established a disturbed depth above 4 mm.…”

Section: Introductionmentioning

confidence: 99%

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Cathodoluminescence study of ZnO wafers cut from hydrothermal crystals

Mass

Avella

Jiménez

et al. 2008

Journal of Crystal Growth

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. (From -To) REPORT DATE (DD-MM-YYYY) 22-11-2007 REPORT TYPE Journal Article DATES COVERED SPONSOR/MONITOR'S ACRONYM(S) AFRL-RY-HS SPONSOR/MONITOR'S REPORT NUMBER(S) AFRL-RY-HS-TP-2008-0018 DISTRIBUTION / AVAILABILITY STATEMENTDISTRIBUTION A: APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. SUPPLEMENTARY NOTESThe U. S. Government is joint author of this work and has the right to use, modify, reproduce, release, perform, display, or disclose the work. ZnO is a wide bandgap semiconductor with very promising expectation for UV optoelectronics. The existence of large crystals should allow homoepitaxial growth of ZnO films for advanced optoelectronic devices. However, the ZnO substrates are not yet mature. Both defect induced by growth and by polishing together with the high reactivity of the surface are problems to their industrial application. Cathodoluminescence (CL) was used to probe the quality of substrates from two different suppliers. The surface damage was studied by varying the penetration depth of the electron beam, allowing to observe significant differences between the two samples within a 0.5-mm-thick surface layer. CL spectra show a complex band (P1) at _3.3 eV composed of two overlapped bands (3.31 and 3.29 eV) related to point defects (PD) and the 1-LO phonon replica of the free exciton (FX-1LO). This band (P1) is shown to be very sensitive to the presence of defects and the surface and thermal treatments. Its intensity compared with the excitonic band intensity is demonstrated to provide criteria about the quality of the substrates. SUBJECT TERMS AbstractZnO is a wide bandgap semiconductor with very promising expectation for UV optoelectronics. The existence of large crystals should allow homoepitaxial growth of ZnO films for advanced optoelectronic devices. However, the ZnO substrates are not yet mature. Both defect induced by growth and by polishing together with the high reactivity of the surface are problems to their industrial application. Cathodoluminescence (CL) was used to probe the quality of substrates from two different suppliers. The surface damage was studied by varying the penetra...

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Section: Resultssupporting

confidence: 91%

Section: Experimental Setup and Samplesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Cathodoluminescence study of ZnO wafers cut from hydrothermal crystals

Mass

Avella

Jiménez

et al. 2008

Journal of Crystal Growth

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Application of predominance diagrams in melt growth of oxides

Ganschow

Schulz

Klimm

et al. 2010

Cryst. Res. Technol.

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Equilibrium thermodynamic calculations are used to construct predominance diagrams of the Ti−O, Cr−O, and Zn−O systems and implications for the growth of Ti:Sapphire, ruby, and ZnO crystals are discussed. For each of these systems, a growth atmosphere yielding an oxygen partial pressure that stabilizes the desired oxidation state of the metal is proposed on the basis of the performed computations. The effectiveness of these atmospheres is demonstrated in crystal growth experiments.

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Homoepitaxy of ZnO: from the substrates to doping

Neumann

Lautenschläger

Graubner

et al. 2007

Physica Status Solidi (b)

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We report on the homoepitaxial growth of ZnO thin films by chemical vapor deposition techniques. The preparation of the ZnO substrates after mechanical polishing employed a high temperature annealing step which produced atomically flat surfaces and removed all of the surface and subsurface damage. Two dimensional epitaxial growth was achieved without an additional buffer layer. The substrate had a rocking curve with a full width at half maximum of 27″ which can be compared with that of the film of 17″. The films had superior band edge luminescence as compared with the substrate for which the green luminescence band is dominating. The impurity content in the substrates especially Li is reduced by the high temperature annealing step and drops further close to the detection limit in the films. The low substrate temperatures around 660 °C allow for the incorporation of nitrogen on oxygen site as a shallow acceptor.

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Issues in ZnO homoepitaxy

Cited by 50 publications

References 8 publications

Cathodoluminescence study of ZnO wafers cut from hydrothermal crystals

Cathodoluminescence study of ZnO wafers cut from hydrothermal crystals

Application of predominance diagrams in melt growth of oxides

Homoepitaxy of ZnO: from the substrates to doping

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