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ZnO based oxide system Zn1−x−yBexMgyO has been prepared by pulsed laser deposition. By incorporating different amounts of beryllium and magnesium into ZnO, the bandgap of ZnBeMgO has been modulated from 3.7 to 4.9 eV continuously. The crystal quality of ZnBeMgO film has been improved significantly comparing with that of either ZnMgO or BeZnO. These ZnBeMgO films are promising for fabricating high-efficiency optoelectronic devices such as solar-blind UV detectors.

Published by the AIP Publishing Articles you may be interested inInfluence of lattice strain on charge/orbital ordering and phase separation in Pr0.7(Ca0.6Sr0.4)0.3MnO3 thin films J. Appl. Phys. 115, 17D708 (2014); 10.1063/1.4863383 Temperature dependence of nanometer-size metallic phase texture and its correlation with bulk magnetic and transport properties and defects of a (La0.4Pr0.6)0.67Ca0.33MnO3 film Appl. Phys. Lett. 101, 022404 (2012); 10.1063/1.4733666 Strain effect caused by substrates on phase separation and transport properties in Pr0.7(Ca0.8Sr0.2)0.3MnO3 thin films J. Appl. Phys. 111, 07D721 (2012); 10.1063/1.3678297 Phase separation and enhanced magnetoresistance in the strained epitaxial La0.625Ca0.375MnO3 (001) films J. Appl. Phys. 111, 066104 (2012); 10.1063/1.3695376 Magneto-and electro-resistance effects in phase separated Pr0.55(Ca0.65S0.35)0.45MnO3 films

We have presented a detailed resonant Raman scattering investigation for the alloying effect in hexagonal Zn1−xMgxO (x⩽0.323) thin films grown by pulsed laser deposition. Alloy-induced longitudinal optical (LO) phonon resonance effect has been achieved from the Raman peak shift, lineshape, and intensity through changing the Mg composition and temperature to tune the ZnMgO bandgap. By the aid of theoretical analysis combining with the extrinsic Fröhlich interaction mediated via a localized exciton, we demonstrate the pronounced outgoing resonance behavior for the LO phonons in ZnMgO, where the localized exciton due to alloy disorder dominates the resonance processes.

The resistance switching characteristics of the La0.7Ca0.3MnO3-based devices with the top electrodes of Ag, Ag–Al alloys with the atomic ratios of Ag:Al=2:1 (2AgAl) and Ag:Al=1:2 (Ag2Al), and Al have been investigated. The device with 2AgAl top electrode shows excellent endurance, where more than 1000 cycles of reproducible current-voltage hysteresis with stable high and low resistance states have been observed. Based on Auger electron spectroscopy measurement and the detailed investigation of current-voltage curves of these devices, it is suggested that the oxygen affinity of the metal electrode, which is determined by the chemical component of Ag and Al, has an important influence on the interface structure and the resistance switching endurance. The present work provides a possible way for the improvement of the resistance switching endurance by modulating oxygen affinity of the electrode.

A combination study of structural, optical, and electrical properties has been carried out on N–In codoped p-type ZnO thin films for the origins of shallow level and hole mobility. The observed small activation energy of ∼20meV for the hole concentration corresponds well to the results from photoluminescence and conductivity data, revealing the grain boundary trapping nature of the shallow level. The achieved hole mobility is mainly due to the lack of grain boundary barrier effect, and the codoping yielded weak ionized impurity scattering. The authors have also revealed the scattering and conduction mechanisms in these p-ZnO films.

Lead magnesium niobate-lead titanate (PMN-PT) ferroelectric thin films were deposited on Ir/SrTiO 3 /TiN/Si (001) substrates by oxygen plasma assisted pulsed laser deposition (PLD) method. Effects of the lanthanum strontium cobaltite (LSCO) buffer layer between the PMN-PT film and the Ir layer on the crystallinity, microstructure, ferroelectric properties and electrocaloric effect of the film were investigated. Results show that the LSCO buffer layer can improve the crystallinity and electrocaloric properties effectively. By applying a voltage of 5V to the PMN-PT thin film without the LSCO buffer layer, the changes in the reversible adiabatic temperature measured at room temperature and at 508 K are respectively 0.73 K and 2.13 K, while by introducing a LSCO buffer layer, the corresponding values are increased to 1.41 K and 4.25 K.With the rapid development of the information technology and the micro-electro-mechanical systems (MEMS), the integrated degree of chips increase rapidly, and the demand on the high-efficiency cooling system is growing correspondingly. 1-4 The electrocaloric (EC) effect is a reversible temperature change of a material under an applied electric field at adiabatic conditions. Since the ferroelectrics have the advantages of giant electrocaloric effect, high energy changes efficiency and environmental-friendly, the ferroelectrics materials have been receiving increased interests in potential on-chip cooling system. 1-2 For example, Shaobo and Yanqiu 5 reported that the PMN-PT relaxor ferroelectric ceramics possess a large electrocaloric effect of T = 1.71 K at 291 K and 16 kV cm −1 . Rozic et al. 6 demonstrated that the considerable electrocaloric effect indeed exists in bulk materials as well as films. Compared with bulk materials, which usually required large operating voltage to obtain electrocaloric temperature change, the electrocaloric thin film can produce giant EC effect under very low operating voltage, thus more suitable for many practical applications. 3-7 The giant EC effect in thin film form PbZr 0.95 Ti 0.05 O 3 (PZT) and 0.9 PbMg 1/3 Nb 2/3 O 3 -0.1 PbTiO 3 (PMN-PT) were first reported by Mischenko et al. 1,3 * Corresponding Author. PbMg 1/3 Nb 2/3 O 3 -PbTiO 3 (PMN-PT) solid solution is a well-known relaxor ferroelectric, which exhibit excellent dielectric, piezoelectric and pyroelectric properties. 8-12 PMN-PT has a morphotropic phase boundary (MPB) separating the rhombohedral phase from the tetragonal phase at around 33% PbTiO 3 . It has been reported that the compositions near the MPB of this system show good pyroelectric behavior. 13-14 So it is plausible that the PMN-PT near MPB composition also shows a promising electrocaloric effect. 15 Many deposition method have been employed to prepare PMN-PT thin films, including sol-gel, chemical vapor deposition, sputtering and pulse laser deposition. [16][17][18][19][20] However, due to the low crystallinity, the electrical and mechanical properties of PMN-PT thin films are usually much poorer than that of bulk materials. In th...

Ba 0.6 Sr 0.4 Ti 1 − x Al x O 3 (BSTA, x=0, 3 at. %, 6 at. %) thin films have been prepared on Ir∕MgO-buffered silicon substrates by pulsed-laser deposition. All-epitaxial growth of BSTA∕Ir∕MgO∕Si heterostructures has been evidenced by x-ray diffraction and reflection high-energy electron diffraction. A large reduction in the leakage current density of BSTA thin films was observed by aluminum doping. For 3 at. % Al-doped BSTA thin films, the dominant conduction mechanism shows space-charge-limited current behavior at a low electric field, where the trap-filled limit field is determined as ETFL=10KV∕cm, while at a high electric field the Poole–Frenkel emission is operative. In contrast, the conduction mechanism for 6 at. % Al-doped BSTA thin film is dominated by field-enhanced Schottky emission.