III-nitride integration on ferroelectric materials of lithium niobate by molecular beam epitaxy

Namkoong, Gon; Lee, Kyoung-Keun; Madison, Shannon M.; Henderson, Walter; Ralph, Stephen E.; Doolittle, W. Alan

doi:10.1063/1.2084340

Cited by 39 publications

(33 citation statements)

References 18 publications

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“…For example, it is possible to grow group III nitrides with spatially varied, absolute polarity control on LN substrates. 2 The dipole orientation can be switched at the nanoscale, bearing a great potential for domain-specific surface chemistry as a route towards the fabrication of nanoscale devices. 3 LN surface charges were found to enable artificial photosynthesis 4 and to drive photocatalytic dye decolorization.…”

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confidence: 99%

Charge compensation by long-period reconstruction in strongly polar lithium niobate surfaces

et al. 2013

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The microscopic structure of the polar (0001) and (0001) surfaces of lithium niobate is investigated by atomic-resolution frequency modulation atomic force microscopy and first-principles calculations. It is found that the surface reconstructs at annealing temperatures sufficiently high to drive off external adsorbates. In particular a ( √ 7 × √ 7)R19.1• reconstruction is found for the (0001) 1 While these applications exploit the peculiar ferroelectric, piezoelectric, photorefractive, and electro-optical properties of the bulk, the strong electric fields and charges at the surfaces of ferroelectric materials have recently attracted the attention of scientists and engineers. For example, it is possible to grow group III nitrides with spatially varied, absolute polarity control on LN substrates.2 The dipole orientation can be switched at the nanoscale, bearing a great potential for domain-specific surface chemistry as a route towards the fabrication of nanoscale devices.3 LN surface charges were found to enable artificial photosynthesis 4 and to drive photocatalytic dye decolorization. 5 The integration of ferroelectric thin films within liquid environments is investigated in the context of laboratory-on-chip device designs, e.g., for localizing, sensing or activating charged biomolecules.6 High surface electric fields due to pyroelectricity were found to efficiently pole electro-optic polymers 7 and to lead to the reversible fragmentation and self-assembling of nematic liquid crystals. 8 Despite many exciting applications, our actual knowledge of the LN surface atomic structure and the associated surface electric field and surface charge is remarkably limited. LiNbO 3 can be thought of as a stapling of Nb-O 3 -Li trilayers along the [0001] direction (Fig. 1). This order gives rise to a spontaneous electric dipole moment and strongly polar (0001) and (0001) surfaces, commonly referred to as negative and positive Z cut, respectively. Using electron diffraction, Yun et al. 9 found no indication for reconstructions on LN(0001) surfaces at ambient conditions. From ion scattering spectroscopy it was concluded that both Z-cut surfaces are oxygen terminated. 9 On the other hand, coaxial impact-collision ion scattering suggested a Nb surface termination.10,11 The experimental investigations are hindered by the extremely challenging preparation and analysis conditions of strongly polar surfaces of insulating materials: Charging effects preclude the application of electron tunneling or diffraction techniques and unscreened surface charges hinder atomic force microscopy. Nonetheless, reconstructions in surfaces commonly referred to as weakly polar surfaces such as the SrTiO 3 (001) and BaTiO 3 (001), have been recently demonstrated by STM 12,13 and transmission electron microscopy 14 techniques. Moreover, the structural and physical properties of polar surfaces are strongly temperature dependent. 15 Only recently, atomic resolution images of the LN(0001) surface have been obtained by frequency modulation atomic force micro...

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Charge compensation by long-period reconstruction in strongly polar lithium niobate surfaces

et al. 2013

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“…Growth regimes for nitride heteroepitaxy on LiNbO 3 substrates require further optimization to prevent potential reduction of the oxide substrates and formation of unwanted LiNb 3 O 8 layers at the heterointerface [2]. In this paper we report results of GaN heteroepitaxy on LiNbO 3 substrates with different orientation: z-cut and x-cut.…”

Section: Introduction Epitaxial Growth Of Gan On Linbomentioning

confidence: 96%

“…substrates attracts attention due to potential applications of this heterostructure for monolithic integration of materials with complimentary optical and electronic properties [1,2]. At the same time, studies of GaN deposition on LiNbO 3 are in a mainstream of the quest for alternative substrates for nitride epitaxy.…”

Section: Introduction Epitaxial Growth Of Gan On Linbomentioning

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GaN thin films on z‐ and x ‐cut LiNbO₃ substrates by MOVPE

Ougazzaden

Moudakir

Aggerstam

et al. 2008

Phys. Status Solidi (c)

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We report epitaxial growth of GaN layers on z ‐ and x ‐cut LiNbO3 substrates using MOVPE. GaN layers with the thickness of 450 nm were characterized using X‐ray diffraction. For both, z‐ and x‐ cut orientations of LiNbO3 substrates, the GaN layers have c‐axis orientation normal to the substrate plane and the in‐plane lattice orientation of GaN layers coincides with the primary axes of LiNbO3 substrates. Although GaN layers exhibit almost complete strain relaxation, the residual compressive strain determined with respect to a free‐standing GaN is of the order of +0.37% and +0.2% for z ‐ and x ‐cut substrates, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…To overcome this problem LiNbO 3 (LN) has been recently proposed as a new substrate. LN is characterized by a relatively small lattice mismatch with respect to GaN and an outstanding cost-performance ratio [3][4][5]. The (0001) plane of LN has, just like α-Al 2 O 3 , hexagonal symmetry and provides a nominal lattice mismatch of only 6.8% with the GaN (0001) plane, which results in a better GaN crystal quality.…”

Section: Introductionmentioning

confidence: 99%

GaN growth on LiNbO₃ (0001) – a first‐principles simulation

Sanna

Schmidt

2010

Phys. Status Solidi (c)

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The growth of GaN on the LiNbO3 (0001) surface is simulated by means of first‐principles total‐energy calculations. Firstly the adsorption of single N and Ga monolayers is investigated and then the layer‐by‐layer growth of GaN on the polar substrate within different orientations is modeled. While adsorbing a N layer does not heavily affect the substrate morphology, the adsorption of a Ga layer causes a rearrangement of the atomic structure. Furthermore the N layer is more strongly bound to the substrate than the Ga layer. On the basis of our results, we propose a microscopic model for the GaN/LiNbO3 interface. The GaN and LiNbO3 (0001) planes are parallel, but rotated by 30° each other, with in‐plane epitaxial relationship [10$ \bar 1 $0]GaN II [11$ \bar 2 $0] LiNbO 3. In this way the (0001) calculated in‐plane lattice mismatch between GaN and LiNbO3 is minimal and equal to 6.79% of the GaN lattice constant. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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III-nitride integration on ferroelectric materials of lithium niobate by molecular beam epitaxy

Cited by 39 publications

References 18 publications

Charge compensation by long-period reconstruction in strongly polar lithium niobate surfaces

Charge compensation by long-period reconstruction in strongly polar lithium niobate surfaces

GaN thin films on z‐ and x ‐cut LiNbO₃ substrates by MOVPE

GaN growth on LiNbO₃ (0001) – a first‐principles simulation

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III-nitride integration on ferroelectric materials of lithium niobate by molecular beam epitaxy

Cited by 39 publications

References 18 publications

Charge compensation by long-period reconstruction in strongly polar lithium niobate surfaces

Charge compensation by long-period reconstruction in strongly polar lithium niobate surfaces

GaN thin films on z‐ and x ‐cut LiNbO3 substrates by MOVPE

GaN growth on LiNbO3 (0001) – a first‐principles simulation

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GaN thin films on z‐ and x ‐cut LiNbO₃ substrates by MOVPE

GaN growth on LiNbO₃ (0001) – a first‐principles simulation