المؤلفون: Mandal, Animesh^1,2 (AUTHOR) manimesh@iisc.ac.in, Banpurkar, Arun G.³ (AUTHOR), Shinde, Shashikant D.⁴ (AUTHOR), Jejurikar, Suhas M.⁵ (AUTHOR)

المصدر: Journal of Applied Physics. 7/14/2024, Vol. 136 Issue 2, p1-13. 13p.

مصطلحات موضوعية: *ZINC oxide thin films, *ZINC oxide films, *ENERGY levels (Quantum mechanics), *THIN films, *PULSED laser deposition, *SUBSTRATES (Materials science), *NANOWIRES

مستخلص: Pristine and dysprosium-doped ZnO thin films, highly c-axis oriented, were grown on a c-Al2O3 substrate using the pulsed laser deposition technique. During the deposition process, the growth was impacted by changes in the oxygen partial pressure. The structural, optical, and compositional properties of the pristine and dysprosium-doped ZnO thin films were systematically characterized using various state-of-the-art experimental techniques. The crystallinity associated with these films was observed to be highly dependent on the oxygen partial pressure maintained during the growth process. An average optical transparency of more than ∼90% in the visible spectral range (i.e., 400–800 nm) was observed for all specimens. For doped specimens, expected intra-4fn emissions of (dysprosium) Dy3+ ions that emanated from the 4F9/2 energy state were observed in room-temperature photoluminescence spectra under direct excitation. The Jacobian-transformed wavelength-to-energy plot for Dy-doped ZnO thin films in the UV-Visible region revealed intriguing findings. Specifically, it depicted a prominent peak at 2.82 eV, indicative of the energy state of Dy3+ ions, alongside intense band-edge emission and various defect-related emissions. The intensity of these transitions was observed to depend on the oxygen partial pressure kept during deposition. An x-ray photoelectron spectroscopy analysis of the doped specimen confirmed the +3 oxidation state of dysprosium into the ZnO matrix. These results provide a promising approach for controlling the doping and growth strategy of Dy-doped ZnO thin films, thereby opening up a wide range of applications and enhancement for next-generation optoelectronic devices. [ABSTRACT FROM AUTHOR]

المؤلفون: Piotrowicz, C.^1,2 (AUTHOR) clementine.piotrowicz@cea.fr, Mohamad, B.¹ (AUTHOR), Malbert, N.² (AUTHOR), Bécu, S.¹ (AUTHOR), Ruel, S.¹ (AUTHOR), Le Royer, C.¹ (AUTHOR)

المصدر: Journal of Applied Physics. 5/7/2024, Vol. 135 Issue 17, p1-11. 11p.

مصطلحات موضوعية: *METAL oxide semiconductor capacitors, *MODULATION-doped field-effect transistors, *METAL oxide semiconductor field-effect transistors, *GALLIUM nitride, *ELECTRON mobility, *COMPUTER-aided design, *PLASMA etching, *STRAY currents

مستخلص: This paper provides a comprehensive study of the impact of the gate recess depth (RD) on the GaN-on-Si MOS-HEMTs DC performances. IDS = f(VGS) and IDS = f(VDS) measurements are conducted at 25 and 150 °C, respectively, in forward and blocking modes. The gate recessed depth (50, 150, and 350 nm) is modulated by adjusting the plasma etching time, which is a critical step for improving the dielectric/GaN interface quality and the gate channel electron mobility. Three distinct regions can be defined separately: the bottom, the sidewall, and the corner region being the junction between the two previous regions. To assess the impact of gate recessed depth (RD) on the several mobilities around the gate cavity first, we applied our previous methodology allowing us to extract the bottom (μbot) and the entire sidewall region mobility (μT), without distinction from the corner. The mobility of the transverse region was found surprisingly to increase with deeper RD. To gain insight into the impact of the RD on this transverse section, a new extraction methodology is proposed to extract separately the gate corner (μcorner) and sidewall (μSW) mobility. These extractions show that the corner mobility is found to be reduced compared to the sidewall one (μcorner < μSW) evidencing the different weighting contributions over the transverse mobility. Moreover, these mobilities are found to be more degraded compared to the bottom one, highlighting the different contributions on the on-state resistance (RON). Indeed, the on-state resistance is lowered with the shallower RD due to the reduced sidewall resistance contribution (lower sidewall length) and despite the incremental contribution of the bottom resistance (larger effective gate length). However, the shallower RD shows an increase in the drain–source leakage current in reason of a lower gate electrostatic control. Technology Computer Aided Design (TCAD) simulations of the three RD morphologies are carried out to validate the experimental trends and the proposed methodology. [ABSTRACT FROM AUTHOR]

المؤلفون: Sharma, Rishav^1,2 (AUTHOR), Baraik, Kiran^1,3 (AUTHOR), Srivastava, Himanshu^1,3 (AUTHOR), Mandal, Satish Kumar⁴ (AUTHOR), Ganguli, Tapas^1,3 (AUTHOR), Jangir, Ravindra^1,3 (AUTHOR) ravindrajangir@rrcat.gov.in

المصدر: Journal of Applied Physics. 7/14/2024, Vol. 136 Issue 2, p1-9. 9p.

مصطلحات موضوعية: *MODULATION-doped field-effect transistors, *METAL oxide semiconductors, *MAGNETRON sputtering, *THIN films, *CONDUCTION bands, *SUBSTRATES (Materials science)

مستخلص: Herein, we report epitaxial growth of p-type Ni doped gallium chromium oxide thin film on Al2O3 substrates and studied its band alignment properties with that of the substrate. Thin films are grown using the magnetron-sputtering technique. Synchrotron-based XRD measurements, performed in the coplanar and non-coplanar geometries, confirm high-quality single domain epitaxial growth of p-type α-GaCrO3:Ni. Pendellosung oscillations around the Bragg peak and transmission electron microscopy reveal the high interfacial quality of p-type α-GaCrO3:Ni films with the substrate. Thin film, thickness ∼200 nm, shows around 70% average transmission. The values of valence band and conduction band offsets are determined to be 2.79 ± 0.2 and 0.51 ± 0.2 eV, respectively, which confirm straddling gap band alignment at the heterojunction. This type of alignment creates a threshold barrier for the selective charge carriers and is useful in enhancing the performance of a wide range of devices, including UV photodetectors, metal oxide semiconductor high electron mobility transistors, and light emitters. [ABSTRACT FROM AUTHOR]

المؤلفون: Kubota, Masato¹ (AUTHOR) kubota.masato@jaea.go.jp, Kato, Seiichi² (AUTHOR)

المصدر: Journal of Applied Physics. 7/14/2024, Vol. 136 Issue 2, p1-5. 5p.

مصطلحات موضوعية: *DISTRIBUTION (Probability theory), *ALUMINUM oxide

مستخلص: Amorphous alumina resistance random-access memory is a promising candidate as a next-generation nonvolatile memory. It is intriguing that the nonvolatile memory function emerges in only amorphous samples, unlike crystalline samples. We studied local structures of amorphous alumina samples and Al 2 O 3 polycrystalline using atomic pair distribution function measurements. We derived the Al–Al, O–O, and Al–O atomic distances for each sample. By comparing them, we revealed that the subtle difference in the local structure significantly influences the performance of a nonvolatile memory function. [ABSTRACT FROM AUTHOR]

المؤلفون: Singh, Sanjeet Kumar¹ (AUTHOR), Pantano, Diego¹ (AUTHOR), Prebe, Arnaud¹ (AUTHOR), Soldera, Armand¹ (AUTHOR) armand.soldera@usherbrooke.ca

المصدر: Journal of Chemical Physics. 6/14/2024, Vol. 160 Issue 22, p1-10. 10p.

مصطلحات موضوعية: *POLYETHYLENE oxide, *RADIAL distribution function, *MOLECULAR structure, *IONIC conductivity, *COMPARATIVE studies, *DENSITY

مستخلص: Polyethylene oxide (PEO) holds significant importance in the field of batteries due to its high processability, intrinsic properties, and potential for high ionic conductivity. Achieving simulation at different scales is crucial for gaining a comprehensive understanding of its properties and thus improving them. In this context, we conducted a comparative study on the molecular physical structure, thermodynamic, and dynamic properties of PEO using three distinct coarse-grained (CG) procedures and all-atom (AA) simulations. The three CG simulation procedures involved modeling with MARTINI forcefield, SPICA forcefield, and an IBI derived potential from AA simulations. The AA simulation has been performed using the class 2 pcff+ forcefield. The ensuing simulated densities align significantly with the literature data, indicating the reliability of our approach. The solubility parameter from the AA simulation closely corresponds to literature reported values. MARTINI and SPICA yield almost similar solubility parameters, consistent with the similar density predicted by both the forcefields. Notably, SPICA forcefield closely reproduces the intermolecular structure of atomistic systems, as evidenced by radial distribution function (RDF). It also comprehensively replicates the distribution of radius of gyration (Rg) and the end-to-end distance (Re) of the atomistic samples. IBI ranks second to SPICA in emulating the structural properties of the atomistic systems, such as Rg, Re, and RDF. However, IBI falls short in accurately representing the solubility parameter of the amorphous PEO samples, while MARTINI does not provide an accurate representation of the structural properties of the systems. The use of SPICA forcefield results in enhanced dynamics of the systems in comparison with IBI and MARTINI. [ABSTRACT FROM AUTHOR]

المؤلفون: Caupin, Frédéric¹ (AUTHOR) frederic.caupin@univ-lyon1.fr, Ragueneau, Pierre¹ (AUTHOR), Issenmann, Bruno¹ (AUTHOR) bruno.issenmann@univ-lyon1.fr

المصدر: Journal of Chemical Physics. 5/21/2024, Vol. 160 Issue 19, p1-10. 10p.

مصطلحات موضوعية: *THERMODYNAMICS, *DEUTERIUM oxide, *ISOTOPES, *WATER temperature, *SUPERCOOLED liquids, *VALUATION of real property

مستخلص: Light and heavy water show similar anomalies in thermodynamic and dynamic properties, with a consistent trend of anomalies occurring at higher temperatures in heavy water. Viscosity also increases faster upon cooling in heavy water, causing a giant isotope effect, with a viscosity ratio near 2.4 at 244 K. While a simple temperature shift apparently helps in collapsing experimental data for both isotopes, it lacks a clear justification, changes value with the property considered, and requires additional ad hoc scaling factors. Here, we use a corresponding states analysis based on the possible existence of a liquid–liquid critical point in supercooled water. This provides a coherent framework that leads to the collapse of thermodynamic data. The ratio between the dynamic properties of the isotopes is strongly reduced. In particular, the decoupling between viscosity η and self-diffusion D, measured as a function of temperature T by the Stokes–Einstein ratio Dη/T, is found to collapse after applying the corresponding states analysis. Our results are consistent with simulations and suggest that the various isotope effects mirror the one on the liquid–liquid transition. [ABSTRACT FROM AUTHOR]

المؤلفون: Rawat, Ankita¹ (AUTHOR), Pandey, Utkarsh² (AUTHOR), Chourasia, Ritesh Kumar³ (AUTHOR), Rajput, Gaurav¹ (AUTHOR), Pal, Bhola Nath² (AUTHOR), Chourasia, Nitesh K.^1,4 (AUTHOR), Kulriya, Pawan Kumar¹ (AUTHOR) niteshphyzics@gmail.com

المصدر: Journal of Applied Physics. 5/21/2024, Vol. 135 Issue 19, p1-9. 9p.

مصطلحات موضوعية: *THIN film transistors, *INDIUM gallium zinc oxide, *TRANSISTORS, *METALLIC oxides, *LOW voltage systems, *SEMICONDUCTOR junctions

مستخلص: Metal oxide transistors have garnered substantial attention for their potential in low-power electronics, yet challenges remain in achieving both high performance and low operating voltages through solution-based fabrication methods. Optimizing interfacial engineering at the dielectric/semiconductor interface is of utmost importance in the fabrication of high-performance thin film transistors (TFTs). In the present article, a bilayer Ti3C2Tx-MXene/SnO2–semiconductor (Tx stands for surface termination) configuration is used to fabricate a high-performance n-type thin film transistor by using an ion-conducting Li-Al2O3 gate dielectric on a p+-Si substrate, where electrical charges are formed and modulated at the Li-Al2O3/SnO2 interface, and Ti3C2Tx-MXene nanosheets serve as the primary electrical charge channel due to their long lateral size and high mobility. A comparative characterization of two distinct TFTs is conducted, one featuring Ti3C2Tx MXene and SnO2 semiconductor layer and the other with SnO2 only. Notably, the TFT with the Ti3C2Tx MXene layer has shown a significant boost in the carrier mobility (10.6 cm2/V s), leading to remarkable improvements in the on/off ratio (1.3 × 105) and subthreshold swing (194 mV/decade), whereas the SnO2 TFT without the Ti3C2Tx MXene layer shows a mobility of 1.17 cm2/V s with 8.1 × 102 on/off ratio and 387 mV/decade subthreshold swing. This investigation provides a possible way toward the development of high-performance, low-voltage TFT fabrication with the MXene/semiconductor combination. [ABSTRACT FROM AUTHOR]

المؤلفون: Salcedo, Guillermo A.¹ (AUTHOR) guillermo.salcedo@us.af.mil, Islam, Ahmad E.² (AUTHOR) aeislam@ieee.org, Reichley, Elizabeth² (AUTHOR), Dietz, Michael³ (AUTHOR), Schubert-Kabban, Christine M.⁴ (AUTHOR), Leedy, Kevin D.² (AUTHOR), Back, Tyson C.⁵ (AUTHOR), Wang, Weisong³ (AUTHOR), Green, Andrew² (AUTHOR), Wolfe, Timothy¹ (AUTHOR), Sattler, James M.¹ (AUTHOR)

المصدر: Journal of Applied Physics. 3/28/2024, Vol. 135 Issue 12, p1-8. 8p.

مصطلحات موضوعية: *HAFNIUM oxide films, *FERROELECTRICITY, *HYDROFLUORIC acid, *ZIRCONIUM oxide, *HAFNIUM oxide

مستخلص: Ferroelectricity in hafnium zirconium oxide (Hf1 − xZrxO2) and the factors that impact it have been a popular research topic since its discovery in 2011. Although the general trends are known, the interactions between fabrication parameters and their effect on the ferroelectricity of Hf1 − xZrxO2 require further investigation. In this paper, we present a statistical study and a model that relates Zr concentration (x), film thickness (tf), and annealing temperature (Ta) with the remanent polarization (Pr) in tungsten (W)-capped Hf1 − xZrxO2. This work involved the fabrication and characterization of 36 samples containing multiple sets of metal-ferroelectric-metal capacitors while varying x (0.26, 0.48, and 0.57), tf (10 and 19 nm), and Ta (300, 400, 500, and 600 ° C). In addition to the well-understood effects of x and Ta on the ferroelectricity of Hf1 − xZrxO2, the statistical analysis showed that thicker Hf1 − xZrxO2 films or films with higher x require lower Ta to crystallize and demonstrated that there is no statistical difference between samples annealed to 500 and 600 ° C, thus suggesting that most films fully crystallize with Ta ∼ 500 ° C for 60 s. Our model explains 95% of the variability in the Pr data for the films fabricated, presents the estimates of the phase composition of the film, and provides a starting point for selecting fabrication parameters when a specific Pr is desired. [ABSTRACT FROM AUTHOR]

المؤلفون: Haglund-Peterson, Jessica^1,2 (AUTHOR), Aronson, Benjamin L.³ (AUTHOR), Jaszewski, Samantha T.^1,3 (AUTHOR), Habermehl, Scott¹ (AUTHOR), Esteves, Giovanni¹ (AUTHOR), Conley Jr., John F.² (AUTHOR), Ihlefeld, Jon F.^3,4 (AUTHOR), Henry, M. David¹ (AUTHOR) mdhenry@sandia.gov

المصدر: Journal of Applied Physics. 3/7/2024, Vol. 135 Issue 9, p1-7. 7p.

مصطلحات موضوعية: *TUNNEL junctions (Materials science), *ZIRCONIUM oxide, *NONVOLATILE memory, *HAFNIUM oxide, *COMPLEMENTARY metal oxide semiconductors, *SEMICONDUCTOR manufacturing

مستخلص: Ferroelectric tunnel junctions (FTJs) utilizing hafnium zirconium oxide (HZO) have attracted interest as non-volatile memory for microelectronics due to ease of integration into back-end-of-line (BEOL) complementary metal oxide semiconductor fabrication. This work examines asymmetric electrode NbN/HZO/Nb devices with 7 nm thick HZO as FTJs in a memory structure, with an output resistance that can be controlled by read and write voltages. The individual FTJs are measured to have a tunneling electroresistance of 10 during the read state without significant filament conduction formation and reasonable ferroelectric performance. Endurance and remanent polarizations of up to 105 cycles and 20 μC/cm2, respectively, are measured and are shown to be dependent on the cycling voltage. Electrical measurements demonstrate how magnitude of the write pulse can modulate the high state resistance and the read pulse influences both resistance values as well as separation of resistance states. Then, by using two opposite switching FTJ devices in series, a programmable nonvolatile resistor divider is demonstrated. Measurements of these two FTJ unit memory cells show wide applicability to a BEOL microfabrication process for a re-readable, rewritable, and nonvolatile memory cell. [ABSTRACT FROM AUTHOR]

المؤلفون: Le, Tien Trong¹ (AUTHOR) tien.le@anu.edu.au, Yang, Zhongshu¹ (AUTHOR), Liang, Wensheng¹ (AUTHOR), Macdonald, Daniel¹ (AUTHOR), Liu, AnYao¹ (AUTHOR) anyao.liu@anu.edu.au

المصدر: Journal of Applied Physics. 2/14/2024, Vol. 135 Issue 6, p1-7. 7p.

مصطلحات موضوعية: *ALUMINUM oxide films, *SILICON oxide films, *SILICON wafers, *GETTERING, *SILICON solar cells, *ATOMIC layer deposition

مستخلص: Metallic impurities in the silicon wafer bulk are one of the major efficiency-limiting factors in silicon solar cells. Gettering can be used to significantly lower the bulk metal concentrations. Aluminum oxide thin films from plasma-enhanced atomic layer deposition (PE-ALD) have been reported to getter iron from silicon wafers. However, its gettering mechanism and kinetics remain unclear. In this study, by experimentally monitoring the kinetics of iron reduction in the silicon wafer bulk, aluminum oxide gettering of iron is shown to be caused by a segregation mechanism. Fitting the experimental iron reduction kinetics by the simulation of a segregation gettering process based on various diffusion scenarios suggests that the gettering kinetics is limited by both the diffusivities of iron in the silicon wafer bulk and in the aluminum oxide film. The activation energy of the segregation gettering process (negative meaning exothermic reaction) is estimated to be −0.47 ± 0.16 eV for the investigated as-deposited PE-ALD aluminum oxide film at 550–900 °C, and −0.35 ± 0.06 eV at 400–900 °C for the same film after a 400 °C forming gas anneal (FGA), i.e., after activating the passivation effect of the film. Capacitance–voltage measurements of the films indicate a higher surface defect density in the as-deposited films as compared to the FGA-activated films, which suggests a possible correlation between the surface defect density and gettering. [ABSTRACT FROM AUTHOR]