M. Sumets

Effect of Thermal Annealing on Electrical Properties of Si-LiNbO3

The substructure and electrical properties of the films with the thickness up to 2.0 µm deposited on Si by the methods of the radio frequency magnetron and ion-beam sputtering of a LiNbO3 target have been investigated. It has been established that in thermally annealed samples an activated conduction mechanism with variable jump distance takes place. As a result of thermal annealing a decrease in the charge localization centers (CLC) in the LiNbO3 films from Nt=3·1018cm-3 to Nt=3·1016cm-3 occurs.

Sputtering condition effect on structure and properties of LiNbO3 films

Polycrystalline LiNbO3 films were grown on various substrates by the radio-frequency magnetron sputtering (RFMS) method and ion-beam sputtering (IBS) method at different sputtering conditions. Films formed on the substrates situated within erosion zone (plasma effect) manifested textured structure. When plasma effect became insignificant only LiNbO3 films with random size orientation were formed during the RFMS process and IBS process with an increase in the size of the crystallites. Reactive gas pressure as part of plasma effect has a profound effect on the films’ properties. When gas pressure was increased greatly, grain size declined two fold and the average surface roughness of the grown films doubled. At the higher gas pressure Li-poor phase LiNb3O8 appeared along with LiNbO3 during the growth process. As a result, the film texture disappeared. Single phase LiNbO3 films with two-axes (epitaxial) texture are formed on (111)Ag epitaxial film during the RFMS process at the ion assisted conditions.

Charge transport in LiNbO3-based heterostructures

Successful application of the LiNbO3-based heterostructures in the integrated electronics and optoelectronics is mostly determined by the charge transport phenomenon in the LiNbO3 since this affects their basic parameters. Depending on the particular conditions (temperature, applied field, properties of LiNbO3/substrate heterojunction, etc.), various conduction mechanisms occur simultaneously and primarily, they can be divided into two major groups: contact-limited and bulk-limited. Identification and study of the charge transport mechanisms allow deriving the vital physical properties such as the barrier height at LiNbO3 film/substrate interface, charged defect concentration, traps spacing as well as type and drift mobility of the carriers in the LiNbO3 films. In this paper, the conduction mechanisms in LiNbO3-based heterostructures are discussed in detail and electrical parameters are derived.

Electrical properties and local domain structure of LiNbO3 thin film grown by ion beam sputtering method

The nanocrystalline ferroelectric LiNbO3 films on (001) Si substrates with the random orientation of polycrystalline grains and the predominance of the grains with lateral orientation of the polar axis were grown using the ion beam sputtering method. The remanent polarization and the coercive field are 12 µC/cm2 and 29 kV/cm, respectively. The thermal annealing leads to the coarsening of the grains. The appearance of the “local texture,” which gives rise to the unipolarity of the heterostructures caused by the predominance of the one direction in the vertical component of the spontaneous polarization, is investigated.

LiNbO3 films: Potential application, synthesis techniques, structure, properties

The main directions of application and synthesis of lithium niobate (LiNbO3) and the advantages and drawbacks of the synthesis techniques are considered. The results of structural and morphological characteristics appropriate for use in the creation of devices are shown. The tasks for successful implementation of LiNbO3 films into novel devices are formulated.

Electrical conductivity of the LiNbO3 heterostructures grown by ion sputtering method

The polycrystalline LiNbO3 films were grown by the ion-beam sputtering method on (001)Si substrates. Dielectric losses of the grown (001)Si-LiNbO3 arises from conductivity of LiNbO3 films and increases when temperature rises. Ac conductivity of the studied heterostructures is described by the correlated-barrier hopping (CBH) model and it is induced by the jumps of charge carries between charge centers with concentration D = 3,5·1022 m-3.

Electron states in the surface region of gallium arsenide treated in selenium and arsenic vapor

The parameters of charge localization centers in the skin layer of gallium arsenide treated in selenium-arsenic vapor are investigated by deep-layer transient spectroscopy. It is established that the addition of arsenic to the vapor phase slows down the reaction of heterovalent substitution of selenium for arsenic in GaAs and reduces the density of centers in the skin layer of GaAs.

Reconstruction and electron states of a Ga2Se3-GaAs heterointerface

AbstractIt is established by electron microscopy and electron diffraction analysis that the formation of Ga2Se3(110) layers on GaAs(100) and (111) surfaces during heat treatment of the latter in selenium vapor is accompanied by the formation of transition regions with crystallographic orientations [310] and

Dielectric losses and ac conductivity of Si–LiNbO3 heterostructures grown by the RF magnetron sputtering method

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