Manganese-doped tin telluride, Sn1-xMnxTe, initially investigated as diluted magnetic semiconductor, has recently attracted considerable attention as a prospective thermoelectric material. The introduction of manganese was found to modify the valence band electronic structure, resulting in an improvement in the Seebeck coefficient and thus, the figure of merit (ZT). In the paper, we present a synchrotron radiation study of the electronic band structure of Sn0.9Mn0.1Te by resonant photoemission. The contribution of the Mn3d electrons to the valence band (VB), calculated as the difference between the Energy Distribution Curves (EDCs) taken at the maximum and minimum of the Fano resonance for the Mn3p -> Mn3d absorption threshold, shows a Mn3d related contribution at the VB edge, a dominant maximum at 4 eV, as well as a wide satellite structure between 7 and 11 eV. Comparison with undoped SnTe reveals that the introduction of Mn leads to a strong renormalization of the deep valence band states, Sn5s and Te5s, which through their hybridization with the Sn5p and Te5p states influences the shape of the valence band edge and electron effective mass and therefore the ZT value.

We investigated the structural evolution and optical properties of β-Ga_2O_3 crystals implanted with different rare-earth (RE) ions using channeling Rutherford Backscattering Spectrometry, Positron Annihilation, Photoluminescence, and Photoluminescence Excitation spectroscopies. The studies reveal that implantation-induced disorder, accompanying phase transitions, and post-annealing structural recovery are largely insensitive to the implanted RE species. The defect microstructure is also found to be similar for all implanted RE ions. Thermal annealing does not completely remove radiation-induced defects but instead drives their rearrangement into larger defect complexes. Unimplanted (virgin) β-Ga_2O_3 exhibits strong UV-visible emission attributed to oxygen vacancies, whereas the introduction of RE ions produces additional emission lines originating from electronic transitions within RE3+ ions. The results indicate that RE3+ ions are excited through the host conduction band, followed by non-radiative relaxation to the 4f excited states and radiative decay to the respective ground states. Fluence-dependent studies of Yb3+ reveal the onset of concentration quenching, while RE-related emission remains efficient even in the presence of substantial lattice disorder. These findings provide new insight into defect evolution in ion-implanted beta-Ga2O3 and clarify the excitation mechanisms of RE3+ ions, offering guidance for optimizing the optical performance of β-Ga_2O_3:RE materials.

Manganese-doped tin telluride, Sn(1-x)Mn(x)Te, initially investigated as diluted magnetic semiconductor, has recently attracted considerable attention as a prospective thermoelectric material. The introduction of Mn was found to modify the valence band electronic structure, resulting in an improvement in the Seebeck coefficient and thus, the figure of merit (ZT). In the paper, we present a synchrotron radiation study of the electronic band structure of Sn(0.9)Mn(0.1)Te by resonant photoemission. The contribution of the Mn3d electrons to the valence band (VB), calculated as the difference between the Energy Distribution Curves (EDCs) taken at the maximum and minimum of the Fano resonance for the Mn3p - Mn3d absorption threshold, shows a contribution at the VB edge, a dominant maximum at 4 eV, as well as a wide structure between 7 and 11 eV. Moreover, comparison with undoped SnTe reveals strong renormalization of the Sn5p and Te5p electronic states, which certainly influences the shape of the upper part of the valence band and electron effective mass.

The current study was inspired by the observation of separated regions grouping donors and acceptors in ZnO:N, which was reported using photoemission spectroscopy, surface photovoltage, and cathodoluminescence imaging [Phys. Rev. Appl. 2022, 18, 044021; Phys. Status Solidi A 2023, 220, 2200466]. The correspondence of these regions with individual crystallites suggests that strain may have a significant influence on the formation of shallow acceptor levels in ZnO. In the present paper, using density functional theory, we investigate the electronic and diffusion properties of Zn vacancy in the presence of the NOH2 group in ZnO:N from the point of view of the efficient formation of VZnNOH x acceptor complexes. We show that strain noticeably affects the migration properties of zinc vacancy. In particular, compressive strain facilitates the migration of Zn vacancy, and if it is high enough, the migration barrier drops to zero. It is also shown that the VZnNOH x complexes are easily formed in the presence of C i H2 groups. Photoluminescence spectra measured for ZnO:N films showing different strain conditions and cathodoluminescence images support the above conclusions.

A Scanning Photoelectron Microscopy (SPEM) experiment has been applied to ZnO:N films deposited by Atomic Layer Deposition (ALD) under O-rich conditions and post-growth annealed in oxygen at 800 °C. State-of-the-Art spatial resolution (130 nm) allows for probing the electronic structure of single column of growth. The samples were cleaved under ultra-high vacuum (UHV) conditions to open atomically clean cross-sectional areas for SPEM experiment. It has been shown that different columns reveal considerably different shape of the valence band (VB) photoemission spectra and that some of them are shifted towards the bandgap. The shift of the VB maximum, which is associated with hybridization with acceptor states, was found to be correlated with carbon content measured as a relative intensity of the C1s and Zn3d core levels. Generalized Gradient Approximation (GGA) supplemented by +U correction was applied to both Zn3d and O2p orbitals for calculation of the VZn migration properties by the Nudged Elastic Band (NEB) method. The results suggest that interstitial -CHx groups facilitate the formation of acceptor complexes due to additional lattice perturbation.

This study presents investigations of Yb‐doped , an ultrawide bandgap semiconductor with potential use in future power, and optoelectronic devices operating in high‐radiation environments. The research has focused on the problem of structural damage caused by the implantation of Yb ions into three differently oriented crystals and the optical response of created systems. The (001)‐, (010)‐, and (‐201)‐oriented crystals are implanted at three different fluences of 150 keV Yb ions and examined using a variety of experimental techniques: high‐resolution X‐ray diffraction, Rutherford backscattering spectrometry in channeling mode (RBS/c), and Raman and photoluminescence spectroscopies, to provide comprehensive information about studied systems. Furthermore, the RBS/c studies are supported by Monte Carlo simulations. The results show distinctions between differently oriented crystals. In particular, (010)‐oriented crystals are characterized by the lowest concentration of extended defects and the presence of compressive stress. In contrast, samples with the other two orientations exhibit tensile stress and significantly higher levels of extended defects. Interestingly, the PL spectra of (010)‐oriented show the lowest emission from Yb 3+ ions, suggesting that specific types of extended defects, whose formation is more favorable in the other two orientations than in (010), enhance Yb 3+ luminescence instead of suppressing it.

Radiative environments can induce defects in the exposed materials, whose accumulation leads to defect structure transformations and optical quenching. Therefore, their role is crucial for the fabrication of devices. beta-Ga2O3:RE system seems attractive for prospective optoelectronic applications. In this research, structural defects created in the crystal lattice upon Sm ion implantation in (010)-oriented beta-Ga2O3 and the recovery after annealing are investigated. Channeling Rutherford backscattering spectrometry (RBS/c) supported by McChasy simulations and room-temperature photoluminescence (RT-PL) spectroscopy are applied to study the structural and optical changes, respectively. The studies reveal the existence of two different randomly displaced atoms (RDA)-types of defects in the implanted zone and the optical inactivity of Sm-dopant ions. Rapid thermal annealing (RTA) in argon at 800 degrees C for 0.5 min results in the removal of deeply located defects, while the defects closer to the surface are not influenced significantly. RT-PL measurements demonstrate the strong luminescence in the visible and ultraviolet regions of the spectrum.

Charge-trapping memory (CTM) is a viable contender to supersede the floating gate technology in high-density flash memory applications. To this end, very reliable charge storage in CTM should be secured. This requires optimization of trap density, their energy and spatial location as well as a deep understanding of their origin. In this work, we used X-ray photoelectron spectroscopy (XPS) to investigate chemical bonds in nanolaminated and doped HfO2/Al2O3 stacks in an effort to gain insight into the nature of defects in the electron/hole trapping processes. The impact of Al incorporation into the HfO2 and rapid thermal annealing (RTA) in O2 on the composition, stoichiometry and bonding configurations was studied. Incorporation of Al into HfO2 leads to an increased concentration of Hf-suboxides. Subsequent RTA effectively reduces suboxides, enhances the stoichiometry of the HfO2/Al2O3 stacks and facilitates intermixing at the dielectric interface, resulting in the formation of Hf-Al-O bonds. The valence band spectra indicate that both Al incorporation and RTA change the dielectric/Si band alignment in a similar way, lowering the valence band offset. The observed changes were considered in relation to the electrically active defects and traps in the structures.

RE-doped β-Ga2O3 seems attractive for future high-power LEDs operating in high irradiation environments. In this work, we pay special attention to the issue of radiation-induced defect anisotropy in β-Ga2O3, which is crucial for device manufacturing. Using the RBS/c technique, we have carefully studied the structural changes caused by implantation and post-implantation annealing in two of the most commonly used crystallographic orientations of β-Ga2O3, namely the (-201) and (010). The analysis was supported by advanced computer simulations using the McChasy code. Our studies reveal a strong dependence of the structural damage induced by Yb-ion implantation on the crystal orientation, with a significantly higher level of extended defects observed in the (-201) direction than for the (010). In contrast, the concentration and behavior of simple defects seem similar for both oriented crystals, although their evolution suggests the coexistence of two different types of defects in the implanted zone with their different sensitivity to both, radiation and annealing. It has also been found that Yb ions mostly occupy the interstitial positions in β-Ga2O3 crystals that remain unchanged after annealing. The location is independent of the crystal orientations. We believe that these studies noticeably extend the knowledge of the radiation-induced defect structure, because they dispel doubts about the differences in the damage level depending on crystal orientation, and are important for further practical applications.

Zinc oxide (ZnO) is a wide bandgap semiconductor that holds significant potential for various applications. However, most of the native point defects in ZnO like Zn interstitials typically cause an n-type conductivity. Consequently, achieving p-type doping in ZnO is challenging but crucial for comprehensive applications in the field of optoelectronics. In this work, we investigated the electrical and optical properties of ex situ doped p-type ZnO films. The p-type conductivity has been realized by ion implantation of group V elements followed by rapid thermal annealing (RTA) for 60 s or flash lamp annealing (FLA) on the millisecond time scale in nitrogen or oxygen ambience. The phosphorus (P)-doped ZnO films exhibit stable p-type doping with a hole concentration in the range of 1014 to 1018 cm−3, while antimony (Sb) implantation produces only n-type layers independently of the annealing procedure. Microstructural studies of Sb-doped ZnO show the formation of metallic clusters after ms range annealing and SbZn-oxides after RTA.

β-Ga2O3 is an ultra-wide bandgap semiconductor (Eg~4.8 eV) of interest for many applications, including optoelectronics. Undoped Ga2O3 emits light in the UV range that can be tuned to the visible region of the spectrum by rare earth dopants. In this work, we investigate the crystal lattice recovery of (2¯01)-oriented β-Ga2O3 crystals implanted with Yb ions to the fluence of 1 ×1014 at/cm2. Post-implantation annealing at a range of temperature and different atmospheres was used to investigate the β-Ga2O3 crystal structure recovery and optical activation of Yb ions. Ion implantation is a renowned technique used for material doping, but in spite of its many advantages such as the controlled introduction of dopants in concentrations exceeding the solubility limits, it also causes damage to the crystal lattice, which strongly influences the optical response from the material. In this work, post-implantation defects in β-Ga2O3:Yb crystals, their transformation, and the recovery of the crystal lattice after thermal treatment have been investigated by channeling Rutherford backscattering spectrometry (RBS/c) supported by McChasy simulations, and the optical response was tested. It has been shown that post-implantation annealing at temperatures of 700–900 °C results in partial crystal lattice recovery, but it is accompanied by the out-diffusion of Yb ions toward the surface if the annealing temperature and time exceed 800 °C and 10 min, respectively. High-temperature implantation at 500–900 °C strongly limits post-implantation damage to the crystal lattice, but it does not cause the intense luminescence of Yb ions. This suggests that the recovery of the crystal lattice is not a sufficient condition for strong rare-earth photoluminescence at room temperature and that oxygen annealing is beneficial for intense infrared luminescence compared to other tested environments.

Radiation-induced crystal lattice damage and its recovery in wide bandgap oxides, in particular beta-gallium oxide (β-Ga2O3), is a complex process. This paper presents the detailed study of defect accumulation in the β-Ga2O3 single crystal implanted with Ytterbium (Yb) ions and the impact of Rapid Thermal Annealing (RTA) on the defects formed. The (2¯01)oriented β-Ga2O3 single crystals were implanted with eleven fluences of Yb ions ranging from 1 × 1012 to 5 × 1015 at/cm2. Channeling Rutherford Backscattering Spectrometry (RBS/c) was used to study the crystal lattice damage induced by ion implantation and the level of structure recovery after annealing. The quantitative and qualitative analyses of collected spectra were performed by computer simulations. As a result, we present the first defect accumulation curve of β-Ga2O3 implanted with rare earth ion that reveals a two-step damage process. In the first stage, the damage of the β-Ga2O3 is inconspicuous, but begins to grow rapidly from the fluence of 1 × 1013 at/cm2, reaching the saturation at the random level for the Yb ion fluence of 1 × 1014 at/cm2. Further irradiation causes the damage peak to become bimodal, indicating that at least two new defect forms develop for the higher ion fluence. These two damage zones differently react to annealing, suggesting that they could origin from two phases, the amorphization phase and the new crystalline phase of Ga2O3. High-resolution x-ray diffraction (HRXRD) demonstrates the presence of strain and the γ phase of Ga2O3 after implantation, which disappear after annealing.

The electric breakdown of memory capacitors with atomic layer deposited HfO 2 /Al 2 O 3 nanolaminated stacks was investigated by voltage ramp method and constant voltage stress. Two types of capacitors – with 2.4 and 3.5 nm tunnel SiO 2 layer were investigated, before and after O 2 annealing. Breakdown voltages ~ - 30 V were obtained independently of the thickness of SiO 2 . The O 2 annealing seems to increase the charge to breakdown due to higher current through the capacitors. The effect is more pronounced for structures with 3.5 nm tunnel layer. The results indicate that the electric breakdown is mainly determined by Al 2 O 3 blocking layer and HfO 2 /Al 2 O 3 nanolaminate. The electric breakdown is accompanied by positive charge build-up and generation of interface states at SiO 2 /Si interface. The latter process is subdued in the annealed samples.

Rare earth-doped zinc oxide (ZnO:RE) systems are attractive for future optoelectronic devices such as phosphors, displays, and LEDs with emission in the visible spectral range, working even in a radiation-intense environment. The technology of these systems is currently under development, opening up new fields of application due to the low-cost production. Ion implantation is a very promising technique to incorporate rare-earth dopants into ZnO. However, the ballistic nature of this process makes the use of annealing essential. The selection of implantation parameters, as well as post-implantation annealing, turns out to be non-trivial because they determine the luminous efficiency of the ZnO:RE system. This paper presents a comprehensive study of the optimal implantation and annealing conditions, ensuring the most efficient luminescence of RE3+ ions in the ZnO matrix. Deep and shallow implantations, implantations performed at high and room temperature with various fluencies, as well as a range of post-RT implantation annealing processes are tested: rapid thermal annealing (minute duration) under different temperatures, times, and atmospheres (O2, N2, and Ar), flash lamp annealing (millisecond duration) and pulse plasma annealing (microsecond duration). It is shown that the highest luminescence efficiency of RE3+ is obtained for the shallow implantation at RT with the optimal fluence of 1.0 × 1015 RE ions/cm2 followed by a 10 min annealing in oxygen at 800 °C, and the light emission from such a ZnO:RE system is so bright that can be observed with the naked eye.

The charge trapping effects in memory cells with HfO 2 /Al 2 O 3 nanolaminated stacks with two different thicknesses (2.4 and 3.5 nm) of the tunnel SiO 2 layer were investigated. The HfO 2 /Al 2 O 3 stacks were fabricated by atomic layer deposition and received post deposition annealing in O 2 . The structures with 3.5 nm tunnel oxide were found to provide higher density of trapped charges. The obtained trapped negative charge density is -3.56×10 −6 C/cm 2 and the positive one is 4.03×10 −6 C/cm 2 . It is demonstrated that the electron trapping is significantly influenced by the amount of available electrons in the inversion layer. Under illumination, pulses with duration of 1 ms could provide trapped negative charge density equal to ~60% the value obtained at 10 s duration, where a saturation of the trapped charge is found. The hole trapping is not influenced by the illumination of capacitors and it is found to be slower than the electron one. Some aspects of the trapping process as well as some of the peculiarities in the capacitance-voltage curves obtained in the course of the measurements are briefly discussed.

ADVERTISEMENT RETURN TO ARTICLES ASAPPREVEditorialNEXTJaszowiec 2023: The 51st International School and Conference on the Physics of SemiconductorsElżbieta Guziewicz*Elżbieta Guziewicz*Email: [email protected]More by Elżbieta Guziewiczhttps://orcid.org/0000-0001-6158-5258 and Ewa PrzeździeckaEwa PrzeździeckaMore by Ewa PrzeździeckaCite this: ACS Omega 2023, XXXX, XXX, XXX-XXXPublication Date (Web):December 27, 2023Publication History Published online27 December 2023https://doi.org/10.1021/acsomega.3c09024Published 2023 by American Chemical Society. This publication is licensed under CC-BY-NC-ND 4.0. License Summary*You are free to share (copy and redistribute) this article in any medium or format within the parameters below:Creative Commons (CC): This is a Creative Commons license.Attribution (BY): Credit must be given to the creator.Non-Commercial (NC): Only non-commercial uses of the work are permitted. No Derivatives (ND): Derivative works may be created for non-commercial purposes, but sharing is prohibited. View full license*DisclaimerThis summary highlights only some of the key features and terms of the actual license. It is not a license and has no legal value. Carefully review the actual license before using these materials. This publication is Open Access under the license indicated. Learn MoreArticle Views-Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (770 KB) Get e-AlertscloseSUBJECTS:Analytical apparatus,Photonics,Semiconductors,Students,Two dimensional materials Get e-Alerts

According to the present knowledge, the level of zinc oxide conductivity is determined by donor and acceptor complexes involving native defects and hydrogen. In turn, recently published low-temperature cathodoluminescence images and scanning photoelectron microscopy results on ZnO and ZnO/N films indicate grouping of acceptor and donor complexes in different crystallites, but the origin of this phenomenon remains unclear. The density functional theory calculations on undoped ZnO presented here show that strain and surface proximity noticeably influence the formation energy of acceptor complexes, and therefore, these complexes can be more easily formed in crystallites providing appropriate strain. This effect may be responsible for the clustering of acceptor centers only in certain crystallites or near the surface. Low-temperature photoluminescence spectra confirm the strong dependence of acceptor luminescence on the structure of the ZnO film.

In this work, the properties of ZnO films of 100 nm thickness, grown using atomic layer deposition (ALD) on a–(100) and c–(001) oriented Al2O3 substrate are reported. The films were grown in the same growth conditions and parameters at six different growth temperatures (Tg) ranging from 100 °C to 300 °C. All as-grown and annealed films were found to be polycrystalline, highly (001) oriented for the c–Al2O3 and highly (101) oriented for the a–Al2O3 substrate. The manifestation of semi-polar-(101) and polar (001)–oriented ZnO films on the same substrate provided the opportunity for a comparative study in terms of the influence of polarization on the electrical and structural properties of ZnO films. It was found that the concentration of hydrogen, carbon, and nitrogen impurities in polar (001)–oriented films was considerably higher than in semi-polar (101)–oriented ZnO films. The study showed that when transparent conductive oxide applications were considered, the ZnO layers could be deposited at a temperature of about 160 °C, because, at this growth temperature, the high electrical conductivity was accompanied by surface smoothness in the nanometer scale. On the contrary, semi-polar (101)–oriented films might offer a perspective for obtaining p-type ZnO films, because the concentration of carbon and hydrogen impurities is considerably lower than in polar films.

Atomic layer deposition of HfO2 from TDMAH and water or ammonia water at different temperatures below 400 °C is studied. Growth per cycle (GPC) has been recorded in the range of 1.2–1.6 Å. At low temperatures (≤100 °C), the films grew faster and are structurally more disordered, amorphous and/or polycrystalline with crystal sizes up to 29 nm, compared to the films grown at higher temperatures. At high temperatures of 240 °C, the films are better crystallized with crystal sizes of 38–40 nm but grew slower. GPC, dielectric constant, and crystalline structure are improved by depositing at temperatures above 300 °C. The dielectric constant value and the roughness of the films have been determined for monoclinic HfO2, a mixture of orthorhombic and monoclinic, as well as for amorphous HfO2. Moreover, the present study shows that the increase in the dielectric constant of the films can be achieved by using ammonia water as an oxygen precursor in the ALD growth. The detailed investigations of the relationship between HfO2 properties and growth parameters presented here have not been reported so far, and the possibilities of fine-tuning and controlling the structure and performance of these layers are still being sought.