As the first discovered p-type transparent conductive material, copper(I) iodide (CuI) is considered the most competitive p-type candidate in the field of transparent electronics. Herein, we introduced a low-temperature buffer-layer-assisted strategy to grow γ-CuI with significantly improved structural quality and electrical transport properties by pulsed laser deposition. By adjusting the growth temperature, we can manipulate the rotation domain structure, control the hole concentration Nh from 1014 to 1019 cm−3, and achieve mobility μh = 25 cm2 V−1 s−1 being similar to that of bulk CuI. Based on the temperature-dependent Hall-effect measurement, the ionization energy of a shallow acceptor of EI,S = 137 ± 8 meV and that of a deeper acceptor of EI,D = 262 ± 23 meV were determined. This grown strategy not only enables high-quality CuI film preparation, but also to tailor their electrical properties for integration with n-type semiconductors in transparent electronic circuits.

Epitaxial growth of phase-pure and high-quality spinel γ-Ga2O3-based semiconductor thin films has been a big challenge for fundamental research on metastable defective inverse spinel γ-Ga2O3 semiconductors in view of potential device application. We report experimental results on epitaxial growth, microstructural, and electrical transport properties of (001)-oriented nominal γ-(Ga0.8Ge0.2)2O3 alloy semiconductor single crystal thin films with a coherent interface on cubic spinel (001) MgAl2O4 substrates by pulsed laser deposition using a Ge-rich target. Pristine films are found to be composed of about 2 nm thick insulating Ge-rich surface layers and the high-quality epitaxial n-type semiconductor film layers consisting of partially subvalent Ge2+ and Ga1+ cations as well as major components of normal Ge4+ and Ga3+ cations. Epitaxial films exhibit a direct bandgap of about 5.2 ± 0.1 eV and a valence band maximum of about 3.3 ± 0.1 eV below the Fermi level at room temperature. We further report a demonstration of γ-(Ga0.8Ge0.2)2O3 thin film-based metal-semiconductor field-effect transistor (MESFET) with the PtOx/Pt Schottky gate contact realized upon the surface pretreatment by Ar/O2 plasma etching. The MESFET device exhibits a clear field-effect with drain current modulation of about 105 orders of magnitude. This work not only significantly advances the fundamental and application-oriented research on epitaxial spinel γ-Ga2O3-based semiconductor films for practical device application but also offers new insight into microstructural characteristics of ultrawide bandgap spinel oxide semiconductor epitaxial thin films.

BACKGROUND:Lung ultrasound is becoming increasingly important in the diagnosis of acute and chronic lung disease, especially in children and adolescents. In children with cystic fibrosis (CF), conventional radiography or computed tomography (CT) has been the main modality used to evaluate acute pneumonia or the progression of chronic lung disease. This Study aimed to evaluate Lung-Ultrasound as a diagnostic tool for children and adolescents with CF. METHODS:We examined 30 CF patients with lung ultrasound before and after spirometry and compared them with lung ultrasounds of 15 lung-healthy children. We used a comprehensive and complete examination procedure with 12 probe positions to determine the best examination procedure in retrospect. In addition, an acceptance survey was conducted among the children and adolescents after the examination. RESULTS:There was a significant difference in pleural irregularities, B-lines, consolidations and the adapted Peixoto et al. score between CF patients and healthy children before spirometry. We found excellent discrimination between patients and lung-healthy subjects using the Peixoto-score (AUC 0.968), pleural irregularities (AUC 0.890). CF patients had more B-lines, more consolidations, and a higher Peixoto score (mean difference 7.7 points). There was no significant difference in lung ultrasound results in children with CF before and after spirometry. Shortening our extended examination procedure would minimally compromise diagnostic accuracy. The lung ultrasound examination was well accepted by the children. CONCLUSION:We could demonstrate that lung ultrasound is a sensitive and reliable method for assessing pulmonary changes in cystic fibrosis.

To tailor electrical properties of often degenerate pristine CuI, Ni is introduced as alloy constituent. Cosputtering in a reactive, but also in an inert atmosphere as well as pulsed laser deposition (PLD), is used to grow thin films. The Ni content within the alloy thin films is systematically varied for different growth techniques and growth conditions. A solubility limit is evidenced by an additional phase for Ni contents , observed in X‐Ray diffraction and atomic force microscopy by a change in surface morphology. Furthermore, metallic, nanoscaled nickel clusters, revealed by X‐Ray photoelectron spectroscopy and high‐resolution transmission electron microscopy (HRTEM), underpin a solubility limit of Ni in CuI. Although no reduction of charge carrier density is observed with increasing Ni content, a dilute magnetic behavior of the thin films is observed in vibrating sample magnetometry. Further, independent of the deposition technique, unique multilayer features are observed in HRTEM measurements for thin films of a cation composition of . Opposite to previous claims, no transition to n‐type behavior was observed, which was also confirmed by density functional theory calculations of the alloy system.

Anion doping is an efficient method for modifying the electrical property of the p‐type semiconductor CuI. However, adjustment of the hole density is still challenging. Using sputtering and spin coating techniques, well‐controlled S‐doping of CuI thin films has been realized. The spin‐coated samples present a single (111) out‐of‐plane orientation and very high crystallinity, which is comparable with previously reported epitaxial CuI thin films. The sputtered thin films have advantages in surface morphology and conductivity. Substituting S for I can achieve efficient acceptor doping of CuI for both the physical and chemical growth methods. The highest conductivity of CuI appears at 2.0 at% of S doping, and the doping efficiency is influenced by the self‐compensation effect.

Willemite-type Zn2GeO4 is a promising ultrawide bandgap semiconductor material. To date, experimental results on growth and physical properties of epitaxial thin films of willemite-type Zn2GeO4 are not available. Here, we report the heteroepitaxial growth of (00.1)-oriented Zn2GeO4 thin films on c-plane sapphire substrates using pulsed laser deposition. The in-plane orientation relationships are [11.0] Zn2GeO4//[11.0] Al2O3 and [11¯.0] Zn2GeO4//[11¯.0] Al2O3. A 450 nm thick epitaxial film with a surface roughness of 2.5 nm deposited under 0.1 mbar oxygen partial pressure exhibits a full width at half maximum (FWHM) of rocking curve of (00.6) reflex of 0.35°. The direct bandgap is evaluated to be 4.9 ± 0.1 eV. The valence band maximum is determined to be 3.7 ± 0.1 eV below the Fermi level. Together with the density-functional theory band structure calculation, it is suggested that the O 2p orbital and Zn 3d orbital dominantly contribute to the valence band of Zn2GeO4. The steady-state photoluminescence (PL) spectra of the films under 266 nm excitation at room temperature exhibit a broad defect-related emission band centered at 2.62 eV with a FWHM of 0.55 eV. The origin of this native defect-related PL is suggested to correlate with Zn interstitials. This work advances the fundamental study on willemite-type Zn2GeO4 epitaxial thin films for potential device application.

The long-term stability of the optically transparent p-type semiconductor copper iodide is a current challenge. The electrical conductivity of CuI thin films depends critically on the environmental impact. Al2O3 cappings enhance the stability considerably. Systematic studies on Al2O3/CuI heterostructures in dependence of the N-2/O-2 growth pressure show the electrical conductivity of the CuI films being determined by the oxygen diffusion through Al2O3 und CuI. Oxygen seems to be a dominating acceptor in CuI. We traced the diffusion of atmospheric oxygen into CuI with O-18 isotopes.

AbstractDie Langzeitstabilität des optisch transparenten p‐Typ‐Halbleiters Kupferiodid ist eine aktuelle Herausforderung, da die elektrische Leitfähigkeit von CuI‐Dünnfilmen empfindlich auf Umgebungseinflüsse reagiert. Deckschichten aus Aluminiumoxid erhöhen die Stabilität beträchtlich. Systematische Untersuchungen von Al2O3/CuI‐Heterostrukturen in Abhängigkeit der N2‐ oder O2‐Partialdrücke bei der Oxid‐Abscheidung zeigen, dass die elektrische Leitfähigkeit der CuI‐Filme durch die Sauerstoff‐Diffusion in Al2O3 und CuI bestimmt wird. Sauerstoff scheint somit als dominierender Akzeptor in CuI zu wirken. Die Diffusion des Umgebungs‐Sauerstoffs in CuI wurde mittels des 18O‐Isotopes verfolgt.

Amorphous transparent conductors (a-TCs) are key materials for flexible and transparent electronics but still suffer from poor p-type conductivity. By developing an amorphous Cu(S,I) material system, record high hole conductivities of 103-104 S cm-1 have been achieved in p-type a-TCs. These high conductivities are comparable with commercial n-type TCs made of indium tin oxide and are 100 times greater than any previously reported p-type a-TCs. Responsible for the high hole conduction is the overlap of large p-orbitals of I- and S2- anions, which provide a hole transport pathway insensitive to structural disorder. In addition, the bandgap of amorphous Cu(S,I) can be modulated from 2.6 to 2.9 eV by increasing the iodine content. These unique properties demonstrate that the Cu(S,I) system holds great potential as a promising p-type amorphous transparent electrode material for optoelectronics.

Pulsed laser deposition (PLD) is one of the most flexible physical growth techniques for thin films of functional materials at the research and demonstrator level. We describe here a relatively simple and reliable concept of the PLD hardware that allows both deposition on large areas up to 4 in. diameter and deposition of tailored lateral and vertical composition spreads without time-consuming hardware changes. Different PLD approaches have been implemented in various chambers via specific and correlated computer-controlled movements of the target, substrate, and masks in conjunction with an appropriate target phase composition. The design of the chambers benefits from our long-term experience to find the most reliable solutions for the critical mechanical and high-temperature parts.

We investigate α-(AlxGa1-x)2O3 layers deposited by PLD for 0≤x≤1 on a- and m-plane sapphire. RSM measurements reveal a fundamental difference for these planes. Pseudomorphic α-(AlxGa1-x)2O3 on m-plane sapphire shows a shear strain e'5 along the c-axis vanishing on a-plane sapphire. Similarly, only relaxed m-plane α-(AlxGa1-x)2O3 exhibits a global lattice tilt in c-axis direction. Modeling of lattice constants and e'5 as function of x prove the shear strain to be due to the non-vanishing C14 component of the stress-strain tensor for α-(AlxGa1-x)2O3 contributing only for the m-plane. We further explain the occurrence of the lattice tilt and identify possible relaxation mechanisms.

Single crystalline thin films of the transparent, p-type semiconductor copper iodide (CuI) were grown by pulsed laser deposition on SrF2(111) and sodium bromide (NaBr) sacrificial layers to create free-standing CuI films.

We present κ-Ga2O3 layers grown by tin-assisted PLD on highly conductive Al-doped ZnO back contact layers. κ-Ga2O3 deposited on c-sapphire typically exhibits no lateral current flow. Significant currents can only be detected when a vertical current flow through the κ-Ga2O3 layer is enabled by the back contact confirming a strong conductivity anisotropy possibly due to suppressed transport across rotational domain boundaries. Pt/PtOx or Pd/PdOx Schottky contacts and NiO or ZnCo2O4 p-type contacts exhibit rectification ratios up to seven orders of magnitude. Further, we obtain a mean barrier height of ~2.1 eV and ideality factors as low as ~1.3 for Pt/PtOx/κ-Ga2O3 Schottky barrier diodes.

This E4 section focuses on the preparation of thick and thin films of LTS and HTS materials and describes the base technologies used to develop sophisticated electronic and electrical applications. Low-Tc Josephson junctions are already processed into highly integrated planar structures consisting of 10 stacked Nb layers, with minimum feature size of 250 nm. The circuits include up to about 800,000 single junctions and are intended for low-energy-consumption processors and memories in single flux quantum (SFQ) logics. Other highly promising application directions are currently single photon detectors, superconducting spintronics, and hybrid devices of superconductors and other functional materials. Moreover, the more engineering-related coated conductors are also still a hot topic of research and application.

The occurrence of rotational domains is a well-known issue for copper iodide (CuI) that naturally occurs for growth on popular substrates like sapphire. However, this has detrimental effects on the thin film quality like increasing surface roughness or deteriorated transport characteristics due to grain boundary scattering. Utilizing pulsed laser deposition and the in situ growth of sodium chloride (NaCl) and sodium bromide (NaBr) template layers, studies were performed on their potential on suppressing the formation of rotational domains of CuI on c-plane sapphire and SrF2 (111) substrates. Corresponding samples were investigated concerning their epitaxial properties and further characterized regarding (volume) crystalline, morphological, and electrical properties. Particularly for NaBr template layers, fully single-crystalline growth of CuI thin films was obtained and resulted in significantly reduced surface roughness of the CuI layer.

Preferentially (110)-oriented BaTiO3 (BTO) thin films can be achieved by PLD on Y3Fe5O12 (YIG)(100) or Gd3Ga5O12 (GGG)(100) substrates, while on other substrate orientations polycrystalline films are observed.

Pseudomorphic and relaxed α -(Al _x Ga _1-x ) _2 O _3 thin films are grown by combinatorial pulsed laser deposition in the entire composition range on prismatic a- and m-plane α -Al _2 O _3 substrates. Pseudomorphic growth on m-plane sapphire has been achieved for x ≥ 0.45 . A distinct difference between the a- and m-epitaxial plane is observed in reciprocal space map measurements being in agreement with continuum elasticity theory for rhombohedral heterostructures. While pseudomorphic layers on m-plane sapphire show a pronounced shear strain e'_5 along the c -axis direction, relaxed layers exhibit a global lattice tilt in the same direction. Both effects are not present on the a-epitaxial plane. Out-of-plane lattice constants as well as e'_5 are modeled as function of x employing elasticity theory, confirming theoretical values of the elastic stiffness tensor for α -Ga _2 O _3 , especially the non-zero value of the C_14 component. Possible pyramidal slip systems for strain relaxation in c -axis direction are examined to explain and numerically model the difference in lattice tilt for the two substrate orientations. Graphic abstract

Structural properties of rhombohedral α‐(Al x Ga 1− x ) 2 O 3 thin films grown by two combinatorial pulsed laser deposition (PLD) techniques are investigated for the entire composition range. One α‐(Al x Ga 1− x ) 2 O 3 thin film is deposited on a 2 inch in diameter large a‐plane sapphire substrate using the continuous composition spread (CCS) PLD technique to fabricate a thin film with varying Al content ranging between x = 0.13 and x = 0.84. Laterally homogeneous α‐(Al x Ga 1− x ) 2 O 3 thin films exhibiting discrete Al contents are fabricated using radially segmented PLD targets on (11.0) Al 2 O 3 . Independent of the PLD technique, for x ≈ 0.55, a change from relaxed to pseudomorphic growth is observed as confirmed by the evolution of in‐ and out‐of‐plane lattice constants. The crystal structure is studied depending on the cation composition by X‐ray diffraction confirming the fabrication of epitaxial, corundum‐structured thin films.