Defect dynamics and spectral observation of twinning in single crystalline LaAlO3 under subbandgap excitation

Chen, J. Q.; Wang, X.; Lu, Yong-Shen; Barman, A. Roy; You, Guofeng; Xing, Guanru; Sum, Tze Chien; Dhar, S.; Feng, Yue; Ariando, Ariando; Xu, Qing‐Hua; Venkatesan, T.

doi:10.1063/1.3543840

Cited by 21 publications

(24 citation statements)

References 22 publications

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“…This scenario of metallic junction transport as a result of the formation of a defect-related quasiconduction band is consistent with a recent report on metal/LAO/ Nb-STO heterostructures [68]. However, in the thick LAO films on the scale of 100 nm, the defect states exist at roughly 2 eV below the conduction-band edge [68,69], which was also proposed in a first-principles study [46]. In contract, in our Pt/LAO/STO heterostructure with an ultrathin LAO layer, the electronic band structure is modified in a different way by the oxygen vacancies.…”

Section: First-principles Calculationssupporting

confidence: 74%

Nonvolatile Resistive Switching inPt/LaAlO3/SrTiO3Heterostructures

Luo

Turner

et al. 2013

Phys. Rev. X

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Resistive switching heterojunctions, which are promising for nonvolatile memory applications, usually share a capacitorlike metal-oxide-metal configuration. Here, we report on the nonvolatile resistive switching in Pt=LaAlO 3 =SrTiO 3 heterostructures, where the conducting layer near the LaAlO 3 =SrTiO 3 interface serves as the ''unconventional'' bottom electrode although both oxides are band insulators. Interestingly, the switching between low-resistance and high-resistance states is accompanied by reversible transitions between tunneling and Ohmic characteristics in the current transport perpendicular to the planes of the heterojunctions. We propose that the observed resistive switching is likely caused by the electric-field-induced drift of charged oxygen vacancies across the LaAlO 3 =SrTiO 3 interface and the creation of defect-induced gap states within the ultrathin LaAlO 3 layer. These metal-oxide-oxide heterojunctions with atomically smooth interfaces and defect-controlled transport provide a platform for the development of nonvolatile oxide nanoelectronics that integrate logic and memory devices.

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Section: First-principles Calculationssupporting

confidence: 74%

Nonvolatile Resistive Switching inPt/LaAlO3/SrTiO3Heterostructures

Luo

Turner

et al. 2013

Phys. Rev. X

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“…Several recent reports of PL spectra in LaAlO 3 have shown the presence of various types of defects via sharp or broad peaks below the bandgap. Kawabe et al 27 show the presence of a broad PL at ~2.5 eV attributed to oxygen vacancies whereas Chen et al 18 show the presence of two narrow peaks at 1.7 and 1.8 eV and a broad peak at 2.1 eV arising from the displacement of cations from their regular sites. Theoretically, it has been shown that in LaAlO 3 Schottky-like defects that maintain charge neutrality are dominant under all conditions, besides oxygen vacancies and anti-site defects19.…”

Section: Discussionmentioning

confidence: 99%

“…This material is a promising gate insulator for advanced Metal-Oxide-Semiconductor (MOS) devices101112. However, it has been reported to possess localized mid-gap states due to various types of defects — interstitials, vacancies, anti-sites, impurities — causing leakage current and it is important to understand the various defects and their dynamics both experimentally and theoretically13141516171819. On the other hand, lattice strain plays an important role on the defects and their dynamics and hence on the related physical properties20.…”

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confidence: 99%

Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study

Saha

Cao

Motapothula

et al. 2016

Sci Rep

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Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for magneto-optic applications.

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“…Rare earth based oxides, perovskites and their interfaces are of great interest in optical studies as rare earth ions can serve as emission centers for laser systems, such as Nd:YAG (Nd-doped Y 3 Al 5 O 12 )1617. The photoluminescence (PL) properties of the Nd 3+ ion in NGO single crystals were studied by Orera et al 18, where the samples were excited by light from a tungsten lamp.…”

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confidence: 99%

Origin and Quenching of Novel ultraviolet and blue emission in NdGaO3: Concept of Super-Hydrogenic Dopants

Ghosh

Saha

Liu

et al. 2016

Sci Rep

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In this study we report the existence of novel ultraviolet (UV) and blue emission in rare-earth based perovskite NdGaO3 (NGO) and the systematic quench of the NGO photoluminescence (PL) by Ce doping. Study of room temperature PL was performed in both single-crystal and polycrystalline NGO (substrates and pellets) respectively. Several NGO pellets were prepared with varying Ce concentration and their room temperature PL was studied using 325 nm laser. It was found that the PL intensity shows a systematic quench with increasing Ce concentration. XPS measurements indicated that nearly 50% of Ce atoms are in the 4+ state. The PL quench was attributed to the novel concept of super hydrogenic dopant (SHD)”, where each Ce4+ ion contributes an electron which forms a super hydrogenic atom with an enhanced Bohr radius, due to the large dielectric constant of the host. Based on the critical Ce concentration for complete quenching this SHD radius was estimated to be within a range of 0.85 nm and 1.15 nm whereas the predicted theoretical value of SHD radius for NdGaO3 is ~1.01 nm.

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Defect dynamics and spectral observation of twinning in single crystalline LaAlO3 under subbandgap excitation

Cited by 21 publications

References 22 publications

Nonvolatile Resistive Switching inPt/LaAlO3/SrTiO3Heterostructures

Nonvolatile Resistive Switching inPt/LaAlO3/SrTiO3Heterostructures

Magnetic Modes in Rare Earth Perovskites: A Magnetic-Field-Dependent Inelastic Light Scattering study

Origin and Quenching of Novel ultraviolet and blue emission in NdGaO3: Concept of Super-Hydrogenic Dopants

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