ترغب بنشر مسار تعليمي؟ اضغط هنا

Coherent epitaxy of trilayer nickelate (Nd0.8Sr0.2)4Ni3O10 films by high-pressure magnetron sputtering

87   0   0.0 ( 0 )
 نشر من قبل Jiachang Bi
 تاريخ النشر 2021
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

Rare-earth (R) nickelates (such as perovskite RNiO3, trilayer R4Ni3O10, and infinite layer RNiO2) have attracted tremendous interest very recently. However, unlike widely studied RNiO3 and RNiO2 films, the synthesis of trilayer nickelate R4Ni3O10 films is rarely reported. Here, single-crystalline (Nd0.8Sr0.2)4Ni3O10 epitaxial films were coherently grown on SrTiO3 substrates by high-pressure magnetron sputtering. The crystal and electronic structures of (Nd0.8Sr0.2)4Ni3O10 films were characterized by high-resolution X-ray diffraction and X-ray photoemission spectroscopy, respectively. The electrical transport measurements reveal a metal-insulator transition near 82 K and negative magnetoresistance in (Nd0.8Sr0.2)4Ni3O10 films. Our work provides a novel route to synthesize high-quality trilayer nickelate R4Ni3O10 films.



قيم البحث

اقرأ أيضاً

As a unique perovskite transparent oxide semiconductor, high-mobility La-doped BaSnO3 films have been successfully synthesized by molecular beam epitaxy and pulsed laser deposition. However, it remains a big challenge for magnetron sputtering, a wide ly applied technique suitable for large-scale fabrication, to grow high-mobility La-doped BaSnO3 films. Here, we developed a method to synthesize high-mobility epitaxial La-doped BaSnO3 films (mobility up to 121 cm2V-1s-1 at the carrier density ~ 4.0 x 10^20 cm-3 at room temperature) directly on SrTiO3 single crystal substrates using high-pressure magnetron sputtering. The structural and electrical properties of the La-doped BaSnO3 films were characterized by combined high-resolution X-ray diffraction, X-ray photoemission spectroscopy, and temperature-dependent electrical transport measurements. The room temperature electron mobility of La-doped BaSnO3 films in this work is 2 to 4 times higher than the reported values of the films grown by magnetron sputtering. Moreover, in the high carrier density range (n > 3 x 10^20 cm-3), the electron mobility value of 121 cm2V-1s-1 in our work is among the highest values for all reported doped BaSnO3 films. It is revealed that high argon pressure during sputtering plays a vital role in stabilizing the fully relaxed films and inducing oxygen vacancies, which benefit the high mobility at room temperature. Our work provides an easy and economical way to massively synthesize high-mobility transparent conducting films for transparent electronics.
In the prospect of understanding the photoluminescence mechanisms of AlN films doped with erbium and targeting photonic applications we have synthesized non doped and Er-doped AlN films with different crystallized nanostructures by using PVD magnetro n sputtering. Their crystalline morphology and their visible photoluminescence properties were precisely measured.Due to the weak cross-section absorption of rare earths like erbium, it is necessary to obtain an efficient energy transfer mechanism between the host matrix and the rare earth to obtain high luminescence efficiency. Our strategy is then to elaborate some nanostructures that could introduce additional intermediate electronic levels within the gap thanks to the presence of structural defects (point defects, grain boundaries{ldots}) and could lead to energy transfer from the AlN matrix to the rare earth.Doped and non-doped AlN films were prepared by radio frequency magnetron sputtering by using different experimental conditions that will be detailed. It will notably be shown how a negative polarization of samples during deposition allows obtaining crystalline morphologies ranging from the classical columnar structure to a highly disordered polycrystalline structure with grains of several nanometers (nearly amorphous). The nanostructures of the films could be categorized in three types: 1) type 1 was nanocolumnar (width of column ~ 15 nm), 2) type 2 was made of short columns (width of column ~ 10 nm) and 3) the last type was made of equiaxed nanocrystallites (size of grains ~3-4 nm).High-resolution photoluminescence spectroscopy was performed to characterize their optical behaviour. The samples were excited by the laser wavelengths at 458, 488 or 514 nm. A broad photoluminescence band was observed centred around 520 nm in columnar samples. In the same energy range, the highly resolved spectra also showed several sharp emission peaks. This fine structure could be attributed to erbium transitions. This fine structure tended to disappear going from type 1 to type 3 samples. Indeed, the relative intensity of the peaks decreased and their full width at half maximum increased. This change could be related to the density of defects that increased when the size of the grains decreased. The photoluminescence properties of the films in the visible range will be discussed in relation with their structure.
In this work, we studied phase formation, structural and magnetic properties of iron-nitride (Fe-N) thin films deposited using high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (dc-MS). The nitrogen partial pres sure during deposition was systematically varied both in HiPIMS and dc-MS. Resulting Fe-N films were characterized for their microstructure, magnetic properties and nitrogen concentration. We found that HiPIMS deposited Fe-N films show a globular nanocrystalline microstructure and improved soft magnetic properties. In addition, it was found that the nitrogen reactivity impedes in HiPIMS as compared to dc-MS. Obtained results can be understood in terms of distinct plasma properties of HiPIMS.
92 - H. Rinnert 2019
Er-doped aluminum nitride films, containing different Er concentrations, were obtained at room temperature by reactive radio frequency magnetron sputtering. The prepared samples show a nano-columnar microstructure and the size of the columns is depen dent on the magnetron power. The Er-related photoluminescence (PL) was studied in relation with the temperature, the Er content and the microstructure. Steady-state PL, PL excitation spectroscopy and time-resolved PL were performed. Both visible and near infrared PL were obtained at room temperature for the as-deposited samples. It is demonstrated that the PL intensity reaches a maximum for an Er concentration equal to 1 at. % and that the PL efficiency is an increasing function of the magnetron power. Decay time measurements show the important role of defect related non radiative recombination, assumed to be correlated to the presence of grain boundaries. Moreover PL excitation results demonstrate that an indirect excitation of Er 3+ ions occurs for excitation wavelengths lower than 600 nm. It is also suggested that Er ions occupy at least two different sites in the AlN host matrix.
The effect of magnetron power on the room temperature 1.54 $mu$m infra-red photoluminescence intensity of erbium doped AlN films grown by r. f. magnetron sputtering, has been studied. The AlN:Er thin films were deposited on (001) Silicon substrates. The study presents relative photoluminescence intensities of nanocrystallized samples prepared with identical sputtering parameters for two erbium doping levels (0.5 and 1.5 atomic %). The structural evolution of the crystallites as a function of the power is followed by transmission electron microscopy. Copyright line will be provided by the publisher 1 Introduction For some time now, rare-earth (RE)-doped semiconductors represent significant potential applications in the field of opto-electronic technology. Part of this technological interest relies on the shielded 4f levels of the RE ions as they give rise to sharp and strong luminescence peaks [1-5]. Among the RE elements, Er is preferred to its counterparts since the Er ions can produce both visible light at 558 nm (green, one of the primary colours) and IR light at 1.54 $mu$m whose spectrum region coincides with the main low-loss region in the absorption spectrum of silica-based optical fibres, combining so potential applications towards photonic devices and towards optical communication devices operating in the infrared domain. These interesting emissions can however only be exploited when placed into host matrixes. On one side, the shielding of the intra 4f levels prevents the shifting of the RE 3+ energy levels and ensures the frequency emission stability. Moreover the intra 4f transitions are parity forbidden for the isolated ions. Matrixes can render the Er 3+ ions optically active, via a relaxation of selection rules due to crystal field effects. As silicon based materials were tested in the 1960s to the 90s with no clear industrial success it was found that the
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا