Growth of Ga-face and N-face GaN films using ZnO Substrates

Hellman, E. S.; Buchanan, D. N. E.; Wiesmann, D.; Brener, Igal

doi:10.1557/s1092578300001885

Cited by 74 publications

(46 citation statements)

References 13 publications

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“…ZnO has been regarded as one of the most suitable substrates for epitaxial growth of GaN because it has the same wurtzite structure and the lattice mismatches between GaN and ZnO are only 1.9 and 0.4% for a-axis and c-axis [6]. However, it is difficult to grow high-quality GaN films on ZnO because interfacial layers are formed between GaN and ZnO by metalorganic chemical vapor deposition or molecular beam epitaxy due to their high-growth temperatures [7].…”

mentioning

confidence: 99%

Band offsets of polar and nonpolar GaN/ZnO heterostructures determined by synchrotron radiation photoemission spectroscopy

Liu

Kobayashi

Toyoda

et al. 2010

Physica Status Solidi (b)

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C-plane (polar) and m-plane (nonpolar) GaN/ZnO heterostructures have been fabricated by pulsed laser deposition at room temperature, and their electronic structures have been characterized by synchrotron radiation photoemission spectroscopy. Based on the binding energies of core levels and valence band maximum values, the valence band offsets have been found to be 0.7 AE 0.1 and 0.9 AE 0.1 eV for polar and nonpolar GaN/ZnO heterojunctions, respectively. Both heterostructures show type-II band configurations with conduction band offsets of 0.8 AE 0.1 and 1.0 AE 0.1 eV, respectively. GaN and ZnO show upward and downward band bending toward the interface in the nonpolar GaN/ZnO heterojunction. However, both GaN and ZnO show upward band bending toward the interface in the polar heterojunction, which is attributed to negative charges. Analysis of N 1s spectra has revealed that N-O bonds exist only at the polar interface, which probably caused the formation of the negative charges.

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confidence: 99%

Band offsets of polar and nonpolar GaN/ZnO heterostructures determined by synchrotron radiation photoemission spectroscopy

Liu

Kobayashi

Toyoda

et al. 2010

Physica Status Solidi (b)

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“…Thus far, many materials have been proposed as substrates with small lattice mismatches to GaN. [3][4][5][6][7][8][9][10][11][12][13] Among them, ZnO has been regarded as the most promising substrate because ZnO and GaN perfectly share the same crystalline symmetries and the lattice mismatches between them are 1.9% and 0.4% for the a axis and c axis, respectively.…”

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confidence: 99%

Polarity control of GaN grown on ZnO (0001¯) surfaces

Kobayashi

Kawaguchi

Ohta

et al. 2006

Applied Physics Letters

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We have investigated the growth temperature dependence of the structural properties of GaN deposited on O-polarity ZnO (0001¯) using pulsed laser deposition. We have found that atomically abrupt GaN∕ZnO heterointerfaces are obtained at growth temperatures reduced to below 500°C. We have also found that GaN grown at room temperature (RT) exhibits a Ga polarity while that grown at 700°C exhibits a N polarity. However, it is possible to grow Ga-polarity GaN at 700°C by the introduction of a RT buffer layer. First principles calculations well explain how Ga-polarity GaN may be grown on atomically flat O-polarity ZnO surfaces at low temperatures.

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“…The crystal growth apparatus utilizes a modified Bridgeman growth technique including a pressure vessel that contains pressurized oxygen, Figure 3 (1). The apparatus also includes a cooling unit (2) that is situated in the pressure vessel. The cooling unit receives a coolant flow from outside of the vessel (3) and has cooled surfaces that define an enclosure, which receives the ZnO with proper dopant concentration (10 15 -10 20 atoms / cc ).…”

Section: Melt Growth Processmentioning

confidence: 99%

Phosphor-Free Solid State Light Sources

Nause¹,

Ferguson²,

Doolittle³

2007

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The objective of this work was to demonstrate a light emitting diode that emitted white light without the aid of a phosphor. The device was based on the combination of a nitride LED and a fluorescing ZnO substrate. The early portion of the work focused on the growth of ZnO in undoped and doped form. The doped ZnO was successfully engineered to emit light at specific wavelengths by incorporating various dopants into the crystalline lattice. Thereafter, the focus of the work shifted to the epitaxial growth of nitride structures on ZnO. Initially, the epitaxy was accomplished with molecular beam epitaxy (MBE). Later in the program, metallorganic chemical vapor deposition (MOCVD) was successfully used to grow nitrides on ZnO. By combining the characteristics of the doped ZnO substrate with epitaxially grown nitride LED structures, a phosphor -free white light emitting diode was successfully demonstrated and characterized. 3 TABLE OF CONTENTS INTRODUCTIONThe overall project objective is to demonstrate a phosphor -free white LED technology. One goal for this objective is to produce a high quality, doped ZnO substrate as both the lattice-matched substrate for a nitride LED and an emission source for white light generation. An additional goal is the production of a low defect density, high power nitride LED on doped ZnO, which will serve as the optical pump for the doped substrate. The work will be performed both at Cermet and at the Georgia Institute of Technology, with Cermet focusing on the bulk development and Georgia Tech focusing on nitride epitaxy development, which will demand an efficient interaction between the staff at Cermet and Drs. Ferguson and Doolittle at Georgia Tech. RESULTS AND DISCUSSION Quick Results OverviewCermet provided ZnO substrates using its patented crystal growth process and prepared production grade substrates using mechanical and chemi-mechanical polishing processes, which eliminate common defects and provide excellent surface finish, crystallinity, and orientation.Georgia

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Growth of Ga-face and N-face GaN films using ZnO Substrates

Cited by 74 publications

References 13 publications

Band offsets of polar and nonpolar GaN/ZnO heterostructures determined by synchrotron radiation photoemission spectroscopy

Band offsets of polar and nonpolar GaN/ZnO heterostructures determined by synchrotron radiation photoemission spectroscopy

Polarity control of GaN grown on ZnO (0001¯) surfaces

Phosphor-Free Solid State Light Sources

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