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

Ougazzaden, A.; Moudakir, T.; Aggerstam, Thomas; Orsal, G.; Salvestrini, Jean-Paul; Gautier, S.; Sirenko, A. A.

doi:10.1002/pssc.200778490

Cited by 11 publications

(6 citation statements)

References 9 publications

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“…Fast Fourier transformation of the real-space AFM images shows an oblique surface unit cell with lattice parameters of a = 0.75 ± 0.02 nm, b = 0.54 ± 0.02 nm, and α = 94.8 • . Surprisingly, the measured pattern shows some deviation in the oxygen sublattice from the ideal template (Chase 1998) that gives rise to the quasi lattice matched GaN growth on the LiNbO 3 x face demonstrated in Ougazzaden et al (2008). This notwithstanding, as no evidence of long ranging reconstructions at the x-cut has been found experimentally, available computational investigations are restricted to 1 × 1 surface unit cell Schmidt 2010c, Sanna et al 2014b).…”

Section: The X-cutmentioning

confidence: 96%

LiNbO₃surfaces from a microscopic perspective

Sanna

Schmidt

2017

J. Phys.: Condens. Matter

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A large number of oxides has been investigated in the last twenty years as possible new materials for various applications ranging from opto-electronics to heterogeneous catalysis. In this context, ferroelectric oxides are particularly promising. The electric polarization plays a crucial role at many oxide surfaces, and it largely determines their physical and chemical properties. Ferroelectrics offer in addition the possibility to control/switch the electric polarization and hence the surface chemistry, allowing for the realization of domain-engineered nanoscale devices such as molecular detectors or highly efficient catalysts. Lithium niobate (LiNbO) is a ferroelectric with a high spontaneous polarization, whose surfaces have a huge and largely unexplored potential. Owing to recent advances in experimental techniques and sample preparation, peculiar and exclusive properties of LiNbO surfaces could be demonstrated. For example, water films freeze at different temperatures on differently polarized surfaces, and the chemical etching properties of surfaces with opposite polarization are strongly different. More important, the ferroelectric domain orientation affects temperature dependent surface stabilization mechanisms and molecular adsorption phenomena. Various ab initio theoretical investigations have been performed in order to understand the outcome of these experiments and the origin of the exotic behavior of the lithium niobate surfaces. Thanks to these studies, many aspects of their surface physics and chemistry could be clarified. Yet other puzzling features are still not understood. This review gives a résumé on the present knowledge of lithium niobate surfaces, with a particular view on their microscopic properties, explored in recent years by means of ab initio calculations. Relevant aspects and properties of the surfaces that need further investigation are briefly discussed. The review is concluded with an outlook of challenges and potential payoff for LiNbO based applications.

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Section: The X-cutmentioning

confidence: 96%

LiNbO₃surfaces from a microscopic perspective

Sanna

Schmidt

2017

J. Phys.: Condens. Matter

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“…Furthermore, LN has attracted a lot of attention as a substrate for the GaN growth, either for the realization of monolithic optoelectronic amplifiers [7][8][9] or as an alternative substrate ͑to ␣-Al 2 O 3 ͒ for the quasilattice matched growth of GaN. [10][11][12][13] The microscopic understanding of LN surfaces is comparatively poor, however. This is due in part to the lack of surface analysis studies performed in ultrahigh vacuum and in part to the nature of the material itself.…”

Section: Introductionmentioning

confidence: 99%

Lithium niobateX-cut,Y-cut, andZ-cut surfaces fromab initiotheory

2010

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Density-functional theory calculations of the LiNbO 3 ͑2110͒, ͑1100͒, and ͑0001͒ surfaces, commonly referred to as X, Y, and Z cuts, are presented. In case of the Z cut, we find a pronounced dependence of the surface structure and stoichiometry on the direction of the ferroelectric polarization. In contrast, the influence of the chemical potentials of the surface constituents is limited. Rather electrostatics governs the surface stability. Different from the Z cut, the stoichiometry of the X cut and Y cut is clearly dependent on the preparation conditions. The surface charge observed for the nominal nonpolar Y cut is traced back to the formation of a strong surface dipole.

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“…1 On the other hand, ferroelectric ͑FE͒ materials have excellent properties of switchable polarization, piezoelectricity, pyroelectricity, electro-opticity, and voltage tunable dielectric constant. [10][11][12] The progress in atomic-scale control of heterointerfacial structure makes it possible to explore and utilize new physical properties, which arise from the multilayer that are not found in neither of their constituents. This might lead to the possibility of new materials and device design.…”

Section: Introductionmentioning

confidence: 99%

Can we enhance two-dimensional electron gas from ferroelectric/GaN heterostructures?

Zhang

Yang

Liu

et al. 2010

Journal of Applied Physics

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Articles you may be interested inEffects of strain relaxation on bare surface barrier height and two-dimensional electron gas in AlxGa1−xN/GaN heterostructures J. Appl. Phys. 113, 014505 (2013); 10.1063/1.4773334 Residual strain effects on the two-dimensional electron gas concentration of AlGaN/GaN heterostructures J. Appl. Phys. 90, 4735 (2001); 10.1063/1.1408268Two dimensional electron gases induced by spontaneous and piezoelectric polarization in undoped and doped AlGaN/GaN heterostructures Ferroelectric ͑FE͒/semiconductor heterostructures are very promising for future electronic devices. This paper examined several kinds of devices based on heterostructures made from FE and GaN semiconductor. Results showed that although two-dimensional electron gas ͑2DEG͒ density in GaN could be tuned by the polarization of FE, it was harsh to enhance the 2DEG greatly for a practical structure even in theory. We proposed that beside the device process, structure design of the device was also important to 2DEG characteristics. To keep or enhance the 2DEG density need novel materials and/or device structures. Our theory predictions may provide some references to design of new electronic devices and promote experimental studies for FE/GaN heterostructures.

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

Cited by 11 publications

References 9 publications

LiNbO₃surfaces from a microscopic perspective

LiNbO₃surfaces from a microscopic perspective

Lithium niobateX-cut,Y-cut, andZ-cut surfaces fromab initiotheory

Can we enhance two-dimensional electron gas from ferroelectric/GaN heterostructures?

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

Cited by 11 publications

References 9 publications

LiNbO3surfaces from a microscopic perspective

LiNbO3surfaces from a microscopic perspective

Lithium niobateX-cut,Y-cut, andZ-cut surfaces fromab initiotheory

Can we enhance two-dimensional electron gas from ferroelectric/GaN heterostructures?

Contact Info

Product

Resources

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

LiNbO₃surfaces from a microscopic perspective

LiNbO₃surfaces from a microscopic perspective