Martins ZubkinsInstitute of Solid State Physics · Thin Films Laboratory
Martins Zubkins
Doctor of Physics
TCO, photochromic rare-earth oxi-hydride, and antimicrobial coatings deposited by
reactive pulsed-MS and HiPIMS.
About
45
Publications
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123
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Citations since 2017
Introduction
Martins Zubkins currently works as a senior researcher at the Institute of Solid State Physics, University of Latvia in Thin Films Laboratory. Martins does research in thin films deposition by magnetron sputtering (DC, pulse-DC, HIPIMS, reactive sputtering). Current topics are n- and p-type TCO films deposition and characterization, and HiPIMS technology.
Additional affiliations
July 2012 - present
Publications
Publications (45)
An experimental investigation was conducted to explore spectroscopic and structural characterization of semiconducting yttrium oxide thin film deposited at 623 K (± 5K) utilizing reactive pulsed direct current magnetron sputtering. Based on the results obtained from both x-ray diffraction and transmission electron microscope measurements, yttrium m...
This paper reports on the deposition of amorphous and crystalline thin films of Ga2O3 by reactive pulsed direct current magnetron sputtering from a liquid gallium target onto fused (f-) quartz and c plane (c-) sapphire substrates, where the temperature of the substrate is varied from room temperature (RT) to 800{\deg}C. The deposition rate (up to 3...
Crystalline wurtzite zinc oxide (w-ZnO) can be used as a wide band gap semiconductor for light emitting devices and for transparent or high temperature electronics. The use of amorphous zinc oxide (a-ZnO) can be an advantage in these applications. In this paper we report on X-ray amorphous a-ZnOx thin films (~500 nm) deposited at cryogenic temperat...
Zinc-iridium oxide (Zn-Ir-O) thin films have been demonstrated as a p-type conducting material. However, the stability of p-type conductivity with respect to chemical composition or temperature is still unclear. In this study we discuss the local atomic structure and the electrical properties of Zn-Ir-O films in the large Ir concentration range. Th...
The synthesis of the photochromic YHO films is based on the oxidation of deposited yttrium hydride in ambient conditions. The actual state of the films during the deposition process, which is influenced by the deposition pressure and the oxidation caused by the residual gases, is not completely known. We report on the YHxOy thin films deposited by...
The synthesis of the photochromic YHO films is based on the oxidation of deposited yttrium hydride in ambient conditions. The actual state of the films during the deposition process, which is influenced by the deposition pressure and the oxidation caused by the residual gases, is not completely known. We report on the YHxOy thin films deposited by...
Layered two-dimensional (2D) materials, such as p-type WSe2, are potential key materials in the manufacture of the next generation electronic devices. One of the remaining main challenges is the large area growth of high-quality films. A potential large-scale 2D WSe2 synthesis method is conversion (selenization) of a pre-deposited sacrificial precu...
Bulk rhenium trioxide (ReO3) has an unusually high electrical conductivity and, being nanosized, has promising catalytic properties. However, the production of pure ReO3 thin films is challenging due to the difficulty to stabilize rhenium in a 6+ oxidation state. Here we present a novel approach for the deposition of ReOx (x ≈ 1.6–2.9) thin films u...
Triboelectrification of polymers enables mechanical energy harvesting in triboelectric generators, droplet generators, and ferroelectrets. Herein, triboelectric polymers, inspired by the ordering in spider‐silk, with strongly enhanced contact electrification are presented. The ordering in polyether block amide (PEBA) is induced by the addition of i...
Herein, the concept of point of darkness based on polarized light phase difference and absorption of light is demonstrated by simulations using low refractive index and extinction coefficient semiconductor and dielectric, and high refractive index nonoxidizing metal multilayer thin film structures. Several multilayer sensor configurations show grea...
Phase-sensitive and zero-light reflection can be designed not only for single wavelength and single incident angles, but also for broad spectral regions and for variety of incident angles using multilayer thin film structures with low refractive index n semiconductor and dielectric materials, and high n metals.
The synthesis of the photochromic YHO films is based on the oxidation of deposited yttrium hydride in ambient conditions. The actual state of the films during the deposition process, which is influenced by the deposition pressure and the oxidation caused by the residual gases, is not completely known. We report on the YHxOy thin films deposited by...
Tungsten trioxide (WO3) is a well-known electrochromic material with a wide band gap, while rhenium trioxide (ReO3) is a “covalent metal” with an electrical conductivity comparable to that of pure metals. Since both WO3 and ReO3 oxides have perovskite-type structures, the formation of their solid solutions (ReO3–WO3 or RexW1–xO3) can be expected, w...
Many modern applications, including quantum computing and quantum sensing, use substrate-film interfaces. Particularly, thin films of chromium or titanium and their oxides are commonly used to bind various structures, such as resonators, masks, or microwave antennas, to a diamond surface. Due to different thermal expansions of involved materials, s...
Zinc–iridium oxide (Zn–Ir–O) thin films have been demonstrated as a p‐type conducting material. However, the stability of p‐type conductivity with respect to chemical composition or temperature is still unclear. In this study we discuss the local atomic structure and the electrical properties of Zn–Ir–O films in the large Ir concentration range. Th...
The synthesis of the photochromic YHO films is based on the oxidation of deposited yttrium hydride in ambient conditions. The actual state of the films during the deposition process, which is influenced by the deposition pressure and the oxidation caused by
the residual gases, is not completely known. We report on the YHxOy thin films deposited by...
The Tauc’s method [1] is a much-preferred optical band gap (OBG) evaluate method for amorphous (or glassy) materials. However, regardless its clear and simple purpose, it has been routinely and incorrectly applied to study crystalline semiconductors and dielectrics.
In Tauc relation the density of electron states is close to the VB and CB extrema...
Here the concept of point of darkness based on polarized light phase difference and absorption of light is demonstrated by simulations using low refractive index and extinction coefficient semiconductor and dielectric, and high refractive index non-oxidizing metal multilayer thin film structures. Several multilayer sensor configurations show great...
Nanocrystalline zinc peroxide (nano-ZnO2) was synthesized through a hydrothermal process and comprehensively studied using several experimental techniques. Its crystal structure was characterized by X-ray diffraction, and the average crystallite size of 22 nm was estimated by Rietveld refinement. The temperature-dependent local environment around z...
We combined the hybrid density functional theory (DFT) calculations and X-ray absorption spectroscopy (XAS) experiments in the study of the local atomic structure around Ir ions in ZnO thin films with different iridium content. This was then used in the first principles analysis of the thermoelectric properties of material. The emphasis has been pu...
Crystalline wurtzite zinc oxide (w-ZnO) can be used as a wide bandgap semiconductor for light emitting devices and transparent or high temperature electronics. The use of amorphous zinc oxide (a-ZnO) can be an advantage in these applications. In this paper, we report on x-ray amorphous a-ZnO x thin films (∼500 nm) deposited at cryogenic temperature...
This work presents a magnetic field imaging method based on color centres in diamond crystal applied to thin film structure. To demonstrate the capacity of our device we have used it for characterization of magnetic properties in microscopic scale of Cr$_2$O$_3$ thin film structure above and below N\'eel temperature. The obtained measurement result...
Thin films of rhenium trioxide (ReO3) were produced by reactive DC magnetron sputtering from metallic rhenium target followed by annealing in the air in the range of temperatures from 200○C to 350○C. Nanocrystalline single-phase ReO3 films were obtained upon annealing at about 250○C. The thin films appear bright red in reflected light and blue-gree...
In this work, a simple catalyst-free vapour-solid deposition method was applied for controlled deposition of two types (planar and disordered) of continuous
$\text{Bi}_2 \text{Se}_3$
nanostructured thin films on different (fused quartz/glass, mica, graphene) substrates. Characterisation of electron transport (type, concentration and mobility of t...
We present the results of an investigation of ultraviolet, visible, near-infrared (UV-Vis-NIR) and X-ray absorption spectroscopy absorption spectra for zinc-iridium oxide (Zn-Ir-O) thin films with various iridium concentrations deposited by reactive DC magnetron sputtering. It is found that the absorption spectra of zinc-iridium oxide thin films co...
Reactive high power impulse magnetron sputtering (R-HiPIMS) has
been demonstrated as a promising technique for the ZnO:Al (AZO) thin film deposition at low temperature with improved electrical properties
compared to the reactive direct current magnetron sputtering (R-dcMS). However, there are not enough studies about the HiPIMS process using Zn/Al...
In this study the Zn/Al (98:2 wt.%) target was sputtered by rare high power pulses (power unit Melec SIPP2000) in an Ar + O2 atmosphere. The profiles of peak current and the optical emission spectra collected 2 cm above the target surface were detected as a function of electrical parameters (frequency, pulse time, voltage) and oxygen flow. The set...
In this study the Zn/Al (98:2 wt.%) target was sputtered by rare high power pulses (power unit Melec SIPP2000) in an Ar and Ar + O2 atmosphere. The profiles of peak current and the optical emission spectra collected 2 cm above the target surface were detected as a function of electrical parameters (frequency, pulse time, average power) and oxygen f...
A comparative study of heterostructured CuO/CuWO4 core/shell nanowires and double-layer thin films was performed through X-ray diffraction, confocal micro-Raman spectroscopy and electron (SEM and TEM) microscopies. The heterostructures were produced using a two-step process, starting from a deposition of amorphous WO3 layer on top of CuO nanowires...
Zn-Ir-O (Zn/Ir ≈ 1/1) thin films have been reported to be a potential p-type TCO material. It is, however, unknown whether it is possible to achieve p-type conductivity at low Ir content, and how the type and the magnitude of conductivity are affected by the film structure. To investigate the changes in properties taking place at low and moderate I...
Although doped ZnO thin films are promising n-type TCO materials, obtaining p-type ZnO thin films is an important milestone in the development of transparent electronics [1,2]. In this work we will summarize our research on the ZnO-IrO2 thin films [3] and compared with the published theoretical models [4,5]. A series of amorphous and nano-crystalli...
We performed the studies of optical, photoelectric, and transport properties of a hydrothermal bulk n-type ZnO crystal by using the contactless optical techniques: photoluminescence, light-induced transient grating, and differential reflectivity. Optical studies revealed bound exciton and defect-related transitions between the donor states (at ∼60...
Tin tungstate thin films were prepared by dc magnetron sputtering method and studied by x-ray diffraction, confocal microscopy and Raman spectroscopy. It is shown that the films are composed mainly of nanocrystalline a-SnWO4 phase. The possibility to use these films as write-once optical recording media is demonstrated.
Zn-Ir-O thin films on glass and Ti substrates were deposited by reactive DC magnetron sputtering at room temperature. Structural and electrical properties were investigated as a function of iridium concentration in the films. Raman spectrum of Zn-Ir-O (61.5 at.% Ir) resembles the spectrum of rutile IrO2, without any distinct features of wurtzite Zn...
ZnO-IrO2 thin films were deposited on glass by DC reactive magnetron sputtering at room tem-perature. Structural, electrical and optical properties were investigated as a function of iridium atomic concentra-tion in the films. XRD data shows that ZnO-IrO2 thin films are X-ray amorphous and Raman spectrum resembles the spectrum of IrO2, without any...
ZnO:Al (AZO) thin films on glass were deposited by DC reactive magnetron sputtering at approximately 300°C substrate temperature. Structural, electrical and optical properties were investigated as a function of oxygen flow. XRD data shows that AZO thin films are polycrystalline with pronounced c-axis orientation and the grain size increasing with t...
Projects
Projects (5)
Motivated by the high demand for transparent electrical conductors, in this fundamental project we will investigate the topological-like electrical conductivity in Ga2O3 thin films grown via MOCVD on different orientation (including off-axis) sapphire substrates that could be applied in Ga2O3 -based transparent electrodes in ultraviolet optoelectronic devices. The key result will be deeper physical understanding of sapphire substrate crystallographic orientation impact on topological-like metallic conductivity in β– Ga2O3 thin films. Information about epitaxial relations between the film and the substrate together with advanced in-depth film characterization methods might elucidate the surface conductivity mechanism. The origin of a such exceptionally robust conduction merits to be investigated more deeply, because it challenges our current understanding and ways to achieve solar-transparent conducting electrodes in a wide bandgap insulator.
The planned activities include establishment of the MOCVD process for growing epitaxial monocrystalline β–Ga2O3 thin films, investigation of as-grown thin film electrical properties together with detailed structural, compositional and optical characterization of the films by traditional laboratory and advanced synchrotron radiation methods with focus on surface properties and possible donor doping, and large-scale theoretical calculations to elucidate the possible surface conductivity mechanisms.
The goal of this industrial research project is to develop advanced high rate PVD magnetron sputtering and MOCVD technologies for deposition of functional ultrawide-bandgap gallium oxide Ga2O3 and zinc gallate ZnGa2O4 thin films for optoelectronics and electronics applications.
The main goal of the project is to investigate the dependence of physical properties on deposition conditions and illumination in different rare-earth (RE) oxy-hydride thin films for the photochromic applications.
