Volatile resistive switching characteristics of molecular beam epitaxy grown HfO2 thin films

In this work, we have explored the structure, morphology and resistive switching aspects of molecular beamepitaxy grown HfO2 thin films fabricated on highly doped p-type Si substrate at substrate temperatures of 300and 500 ◦C. Both films correspond to the monoclinic phase (P21/c) of HfO2 and exhibit single crystallinestructure with a preferred orientation along (111). The density of the HfO2 layer is found to be 9.1 and 9.2 g/cm3,whereas the root mean square roughness is 1.3 and 2.4 nm in the films grown at 300 and 500 ◦C, respectively.Both films have an average grain size of ~ 140 nm. These HfO2 films demonstrate forming free volatile resistiveswitching behavior with SET voltage of − 3.1 and − 3.6 V, along with the ON/OFF ratio of ~ 2 and ~ 4 for thefilms deposited at substrate temperatures of 300 and 500 ◦C, respectively. For the films grown at 300 ◦C and500 ◦C, the retention time is found to be 20 and 30 s, respectively. Memory device based on HfO2 film withhigher substrate temperature exhibits a better ON/OFF ratio due to higher crystallinity and the availability ofmore oxygen vacancies. A comprehensive mechanism of resistive switching is also discussed in this article,considering the transport of oxygen vacancies and the electromigration of Ag ions

Evaluation of excitation functions of 127I(p,xn) 121,122, 123, 125,127Xe reactions, with particular reference to the production of 127Xe and 123I for medical use

Cross section data for the formation of 121,122,123,125,127Xe via proton induced reactions on 127I were criticallyanalyzed. Three nuclear model codes (TALYS 1.9, ALICE-IPPE, and EMPIRE 3.2) were used to ensure the con-sistency and reliability of the experimental data. Utilizing a well-developed evaluation methodology, a recom-mended fit for each excitation function was obtained, based on theoretical predictions of nuclear models andexperimental cross sections. By using the recommended/reference results, thick target yields were calculated foreach production route and its associated impurity reactions. The indirect production of the radionuclides121,122,123,125I was explored. Special attention was paid to standardization of cross section data for the productionof the medically important radionuclides 127Xe and 123I via the routes 127I(p,n)127Xe and 127I(p,5n)123Xe(EC,β+)123I, respectively

Advances in GeSn alloys for MIR applications

Silicon photonics is widely used for near InfraRed (IR) applications up to 1.6 µm. It plays a key role in short-range optical data communications. However, silicon photonics does not really address mid-IR applications, particularly in the 1.6–5 µm wavelength range. This spectral region is essential for environmental/life sensing and safety applications relying on the optical features of molecular vibrations, the aim being to discern and categorize complex chemical entities. Growing markets for such analysis prioritise sensitivity, specificity, compactness, energy-efficient operation and cost effectiveness. The need for a CMOS-compatible integrated photonic platform for the mid-IR is obvious. Such fully-group-IV semiconductor platform should include low-loss guided interconnects, detectors, modulators and, critically, efficient integrated light sources. This paper provides a comprehensive review of recent advances in GeSn-based mid-IR silicon-compatible devices, including optically and electrically pumped lasers, light-emitting diodes and photodetectors. It also discusses the principles underlying these developments, with focuses on material growth techniques and processing methods