Article
Chemistry, Inorganic & Nuclear
M. Raja, R. Marnadu, M. Balaji, K. Ravikumar, V. Gopala Krishna, Mohanraj Kumar, Ehab El Sayed Massoud
Summary: In this work, gallium-doped tungsten trioxide (Ga@WO3) films and n-Ga@WO3/p-Si diodes were fabricated. The impact of Ga dopant on the physical properties of WO3 films was analyzed. The results showed that higher Ga dopant concentrations led to the presence of Ga in the crystal structure of o-GaWO3. The doped WO3 thin film exhibited higher conductivity and lower activation energy at room temperature. The performance of n-WO3/p-Si diodes was enhanced with Ga dopant concentration.
INORGANIC CHEMISTRY COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
R. Khalil, H. El-Desouky, R. Sobhy, M. K. El-Mansy
Summary: The purpose of this study is to investigate the electrical properties of nano metal-semiconductor heterojunctions based on Poly Vinyl Alcohol (PVA). The results showed that the PVA doped silver nanoparticles (AgNPs-PVA) exhibited both Ohmic contacts and rectifying behavior. The conduction mechanism, dielectric relaxation, and current-voltage behavior of the PVA-AgNPs nanocomposite film were thoroughly examined. The presence of a thin barrier layer on the surface of the dried polymer nanocomposites was found to be responsible for the non-Ohmic electrical behavior.
Article
Engineering, Electrical & Electronic
Sang-Woo Han, Jianan Song, Mansura Sadek, Alex Molina, Mona A. Ebrish, Suzanne E. Mohney, Travis J. Anderson, Rongming Chu
Summary: This study improved the performance of GaN super-heterojunction Schottky barrier diodes by utilizing metal-2DEG sidewall n-ohmic contacts, a pGaN notch near the cathode, and a high-energy Al implantation step. The resulting SHJ-SBD showed a breakdown voltage of approximately 12.5 kV and a specific ON-resistance of 100.8 m Omega.cm(2).
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Chemistry, Physical
Ying-Li Shi, Dong Huang, Francis Chi-Chung Ling
Summary: The difficulty of fabricating ohmic contacts on wide bandgap semiconductors like 13-Ga2O3 is addressed by inserting an n+-doped metal oxide layer between metal and the semiconductor layers. Pulsed laser deposition was used to deposit high crystallinity films of 13-Ga2O3, Erbium-doped ZnO (ErZO), and Gallium-doped ZnO (GZO). Investigation of the band offsets and electrical properties of ErZO/13-Ga2O3 and GZO/13-Ga2O3 heterojunctions revealed nested gap (type I) structures. The solar blind UV detector with a fork electrode structure of as-grown 13-Ga2O3/ErZO/Ti/Au showed superior performance due to ErZO's low band offset and small work function difference.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Chao-Ching Chiang, Xinyi Xia, Jian-Sian Li, Fan Ren, S. J. Pearton
Summary: BCl3 is an efficient plasma etchant for oxides like NiO and Ga2O3, with different etch mechanisms observed for the two materials. The etching of NiO is ion-driven with an energy threshold, while the etching of Ga2O3 has a stronger chemical component without a clear ion energy threshold. Chlorine residues on the etched surfaces can be removed using standard rinsing methods.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2022)
Article
Physics, Applied
Ziqian Qi, Linning Wang, Yingze Liang, Pengzhan Liu, Hongbo Zhu, Yongjin Wang
Summary: This article introduces a solar-blind full-duplex light communication system using 275-nm DUV LEDs, which eliminates electromagnetic interference and solar noise. The system allows a maximum communication distance of 7 meters and supports real-time video and file sharing.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Stephan J. Heise, Hippolyte Hirwa, Marko Stoelzel, Thomas Dalibor, Joerg Ohland
Summary: This study investigates the origin of the N1 signature in Cu(In,Ga)(S,Se)(2) devices by systematically varying the individual layers of the cell stack. The results suggest that the N1 signature is caused by a transport barrier in the buffer/absorber region.
Article
Physics, Applied
A. S. Gudovskikh, A. Baranov, A. Uvarov, D. A. Kudryashov, J-P Kleider
Summary: This study explores the behavior of microcrystalline gallium phosphide (GaP)/Si multilayer structures grown on GaP substrates using plasma enhanced atomic layer deposition (PE-ALD) and plasma-enhanced chemical vapor deposition techniques. Capacitance versus voltage (C-V) profiling, admittance spectroscopy (AS), and deep level transient spectroscopy (DLTS) were employed to investigate the electronic properties of the Schottky barriers formed on the GaP/Si multilayer structures. The results reveal electron accumulation in the Si/GaP wells, with C-V profiling providing qualitative information. However, the frequency dependence of the capacitance limits quantitative determination of the electron concentration and spatial distribution in the wells. AS and DLTS measurements show signatures with activation energies related to the energy barrier at the GaP/Si interface. The AS result corresponds to the conduction band offset at the GaP/Si interface, whereas DLTS probes wells located closer to the Schottky interface. Additionally, DLTS identifies defect levels in GaP, including the Si-Ga + V-P complex and a previously detected defect in single microcrystalline GaP layers grown by PE-ALD.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Jakub Kierdaszuk, Ewelina Rozbiega, Karolina Pietak, Sebastian Zlotnik, Aleksandra Przewloka, Aleksandra Krajewska, Wawrzyniec Kaszub, Maria Kaminska, Andrzej Wysmolek, Johannes Binder, Aneta Drabinska
Summary: The study demonstrates effective gating of graphene at low bias using four-layered graphene/gallium nitride (GaN) Schottky diodes and undoped GaN spacer, suggesting their potential for applications. The observed Raman G band position shift and splitting indicate turbostratic layer stacking and high potential gradient near the Schottky junction. Analysis based on electroreflectance measurements and a modified Richardson equation confirms graphene behavior as a capacitor at reverse bias on n-GaN separated by an undoped GaN spacer.
APPLIED SURFACE SCIENCE
(2021)
Article
Engineering, Electrical & Electronic
Hehe Gong, Feng Zhou, Weizong Xu, Xinxin Yu, Yang Xu, Yi Yang, Fang-fang Ren, Shulin Gu, Youdou Zheng, Rong Zhang, Hai Lu, Jiandong Ye
Summary: Ga2O3 power diodes are crucial in power electronics, and NiO/Ga2O3 p-n heterojunction diodes have demonstrated better performance and stability, with high breakdown voltage and transient current capability superior to past research results.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Chemistry, Multidisciplinary
Sergio Gonzalez, Giovanni Vescio, Juan Luis Frieiro, Alina Hauser, Flavio Linardi, Julian Lopez-Vidrier, Marek Oszajca, Sergi Hernandez, Albert Cirera, Blas Garrido
Summary: In this work, high-quality and low-temperature (below 200 degrees C) metal oxide inks are prepared using inkjet printing technology. The inks are adapted from low-boiling point colloidal suspensions of metal oxide nanoparticles synthesized via flame spray pyrolysis. The resulting inkjet-printed layers exhibit excellent transparency and crystallinity, and the inkjet-printed p-n diode shows efficient rectifying behavior and significant increase in photocurrent under illumination.
ADVANCED MATERIALS INTERFACES
(2023)
Article
Chemistry, Physical
Lukasz Janicki, Ryszard Korbutowicz, Mariusz Rudzinski, Piotr Michalowski, Sebastian Zlotnik, Milosz Grodzicki, Sandeep Gorantla, Jaroslaw Serafinczuk, Detlef Hommel, Robert Kudrawiec
Summary: This study comprehensively investigates the structural and optical properties of GaN subjected to three oxidation modes. The results reveal that all modes lead to the growth of beta-phase Ga2O3, but they differ in surface morphology, growth rate, and oxygen diffusion behavior. Only the vapor oxidation process does not degrade the material underneath the oxide layer.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Roberto Lopez, Gerardo Villa-Sanchez, Israel Vivaldo de la Cruz, Cecilia Encarnacion-Gomez, Victor Hugo Castrejon-Sanchez, Antonio Coyopol, Jorge Edmundo Mastache, Cesar Leyva-Porras
Summary: A p-CuO/n-ZnO heterojunction diode was formed using thermal evaporation and oxidation techniques. The structural, morphological, and electrical properties of CuO and ZnO were studied with various techniques. The diode exhibited low turn-on voltage, breakdown voltage, and specific electrical parameters were calculated.
RESULTS IN PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Owen Kendall, Lesly Melendez, Jiawen Ren, Samantha Prabath Ratnayake, Billy J. Murdoch, Edwin L. H. Mayes, Joel van Embden, Daniel E. Gomez, Arrigo Calzolari, Enrico Della Gaspera
Summary: In this study, spinel copper gallate (CuGa2O4) nanocrystals with an average size of 3.7 nm were synthesized and characterized via a heat-up colloidal reaction. The CuGa2O4 nanocrystals have a band gap of -2.5 eV and exhibit p-type character, which is consistent with ab initio simulations. When deposited as thin films, these novel nanocrystals are shown to be photoactive, generating a clear and reproducible photocurrent under blue light irradiation. The ability to adjust the Cu/Ga ratio within the nanocrystals and its effect on their optical and electronic properties was also demonstrated. These findings position CuGa2O4 nanocrystals as a promising material for optoelectronic applications, including hole transport and light harvesting.
Article
Chemistry, Physical
Jian Li
Summary: The characterization technique presented in the study provides significant improvement over conventional admittance spectroscopy in extracting activation energy Ea and the attempt-to-escape frequency nu(0) for electrically active defects in semiconductor materials. The method involves Arrhenius transformations to match isorate and isothermal scans from the two-dimensional temperature-rate experimental space onto virtual spaces, without the need for frequency/temperature derivatives or Arrhenius plots.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Physics, Applied
Sijun Luo, Lukas Trefflich, Susanne Selle, Ron Hildebrandt, Evgeny Krueger, Stefan Lange, Jingjing Yu, Chris Sturm, Michael Lorenz, Holger Von Wenckstern, Christian Hagendorf, Thomas Hoeche, Marius Grundmann
Summary: This paper reports the heteroepitaxial growth of (00.1)-oriented Zn2GeO4 thin films on c-plane sapphire substrates using pulsed laser deposition. The thin films exhibit [11.0] Zn2GeO4// [11.0] Al2O3 and [1(1) over bar.0] Zn2GeO4//[1(1) over bar.0] Al2O3 in-plane orientation relationships. The measured properties include a rocking curve full width at half maximum of 0.35 degrees, a direct bandgap of 4.9 +/- 0.1 eV, and a defect-related photoluminescence emission centered at 2.62 eV with a FWHM of 0.55 eV. This study enhances our understanding of the physical properties and potential device application of Zn2GeO4 thin films.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Tillmann Stralka, Michael Bar, Fabian Schoeppach, Susanne Selle, Chang Yang, Holger von Wenckstern, Marius Grundmann
Summary: Current probe atomic force microscopy (cp-AFM) measurements reveal the influence of the textured nature of sputtered gamma-CuI (111) thin films on charge carrier transport. The conductive behaviors of grains and grain boundaries (GBs) are differentiated and correlated, showing a clear difference between them. The time-dependent surface changes, possibly caused by atmospheric oxygen, result in the vanishing of charge carrier transport over time.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Sofie Vogt, Clemens Petersen, Max Kneiss, Daniel Splith, Thorsten Schultz, Holger von Wenckstern, Norbert Koch, Marius Grundmann
Summary: This study presents the structural and electrical properties of undoped and doped alpha-Ga2O3 thin films grown on m-plane sapphire. An undoped alpha-Ga2O3 buffer layer was introduced to improve crystal quality and stabilize the alpha-phase at lower substrate temperatures. Donor doping with tin and germanium achieved high electron mobilities. Suitable annealing temperature for ohmic Ti/Al/Au layer stacks was identified, while high annealing temperatures deteriorated the electrical properties of the thin films, indicating the need for low temperature contacting procedures for alpha-Ga2O3-based devices.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Physics, Condensed Matter
Evgeny Krueger, Volker Gottschalch, Gabriele Benndorf, Ron Hildebrandt, Ana Lucia Pereira, Michael S. Bar, Steffen Blaurock, Stefan Merker, Chris Sturm, Marius Grundmann, Harald Krautscheid
Summary: This study presents the epitaxial growth of AgxCu1-xI alloy layers and isolated small crystals on Al2O3 (0001) using the close distance sublimation (CDS) technique. Single-phase gamma-AgxCu1-xI thin films are obtained up to an Ag content of approximately 0.5, with the beta-phase also observed at higher Ag contents. The epitaxial relationships between the deposited AgxCu1-xI layers and the Al2O3 substrate, as well as the structure type, are discussed for different alloy compositions. Additionally, a method for depositing polycrystalline single-phase gamma-AgxCu1-xI thin films for Ag contents up to approximately 0.7 is presented based on the solid-state reaction of AgI layers on Al2O3 (0001) substrate with CuI. Furthermore, it is shown that the near-band-edge emission at 2 K is dominated by excitonic recombination, and the spectral position of the emission profile can be tuned by the alloy composition.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Jon Borgersen, Robert Karsthof, Vegard Ronning, Lasse Vines, Holger von Wenckstern, Marius Grundmann, Andrej Yu Kuznetsov, Klaus Magnus Johansen
Summary: Significant resistivity variations have been observed in oxides subjected to low ion doses, which cannot be explained by bulk defects. A comparative study of In2O3-based oxides revealed correlations between resistivity evolution, low ion doses, and UV illumination. The resistivity drops were attributed to oxygen desorption facilitated by irradiation/illumination, as confirmed by post-irradiation exposure to oxygen atmosphere.
Review
Materials Science, Coatings & Films
Laurenz Thyen, Daniel Splith, Max Kneiss, Marius Grundmann, Holger von Wenckstern
Summary: We introduce a new technique, MARS-PLD, for area-selective physical vapor deposition. By using a movable mask, we can selectively mask any desired area on a substrate to create multinary material composition gradients. We demonstrated the capabilities of this method by fabricating material gradients in (Mg,Zn)O thin films and on predefined two-dimensional patterns.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Nanoscience & Nanotechnology
Evgeny Krueger, Michael Seifert, Volker Gottschalch, Harald Krautscheid, Claudia S. Schnohr, Silvana Botti, Marius Grundmann, Chris Sturm
Summary: We studied the excitonic transition energy E-0 and spin-orbit split-off energy Delta(0) of gamma-AgxCu1-xI alloy thin films using reflectivity measurements at temperatures between 20 K and 290 K. The observed bowing behavior of the E-0 transition as a function of alloy composition is explained based on first-principles band structure calculations. The spin-orbit coupling increases with increasing Ag-content, and the temperature-dependent bandgap shift decreases with increasing Ag-content.
Article
Physics, Applied
Andreas Mueller, Sebastian Henn, Evgeny Krueger, Steffen Blaurock, Harald Krautscheid, Marius Grundmann, Chris Sturm
Summary: We report on the photoluminescence emission in copper iodide bulk single crystals induced by two- and three-photon absorption around 1.525eV. The non-linear optical processes were investigated through density-dependent, steady-state, and time-resolved photoluminescence spectroscopy. We observed that the photoluminescence intensity showed an almost parabolic behavior with the excitation power when the excitation energy corresponded to half of the bandgap energy. We also found a cubic contribution that increased with decreasing excitation energy. The ratio between the two- and three-photon absorption cross sections was determined to be approximately 10(-28) cm(2)s.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Condensed Matter
Marius Grundmann
Summary: This study revisits the problem of potential, electrical field, and charge density in a space charge region. Using the Boltzmann approximation, an analytical asymptotic solution is obtained. The exact solution can be found by numerically integrating an analytical function. A comparison is made with the popular abrupt (or depletion) approximation, and an analytical approximation is provided. The analytical approximation for potential, electrical field, and charge density in a space charge (depletion) region shows good agreement with the (numerically) exact solution.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2023)
Article
Instruments & Instrumentation
Michael Lorenz, Holger Hochmuth, Holger von Wenckstern, Marius Grundmann
Summary: Pulsed laser deposition (PLD) is a highly flexible physical growth technique for thin films of functional materials. This article describes a relatively simple and reliable concept of PLD hardware that enables deposition on large areas (up to 4 inches in diameter) and tailored lateral and vertical composition spreads without the need for time-consuming hardware changes. Different PLD approaches have been implemented in various chambers by using specific and correlated computer-controlled movements of the target, substrate, and masks, along with an appropriate target phase composition.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Nanoscience & Nanotechnology
Fabian Schoeppach, Daniel Splith, Holger von Wenckstern, Marius Grundmann
Summary: In this study, metal-semiconductor field-effect transistor (MESFET) devices based on pulsed laser deposition (PLD) grown In2O3 thin films are reported. These devices exhibit on-off ratios exceeding 6 orders of magnitude and low sub-threshold swing values close to the thermodynamic limit. Oxygen plasma treatment and compensation doping with Mg are used to suppress the accumulation of electrons at the surface of In2O3, which is a major obstacle for its use as an active material in electronic devices.
ADVANCED ELECTRONIC MATERIALS
(2023)
