Organic-inorganic halide perovskites are intrinsically unstable when exposed to moisture and/or light. Additionally, the presence of lead in many perovskites raises toxicity concerns. Herein is reported a thin film of BaZrS3, a lead-free chalcogenide perovskite.Photoluminescence and X-ray diffraction measurements show that BaZrS3 is far more stable than methylammonium lead iodide (MAPbI3) in moist environments. Moisture-and lightinduced degradations in BaZrS3 and MAPbI3 are compared by using simulations and calculations based on density functional theory. The simulations reveal drastically slower degradation in BaZrS3 due to two factorsweak interaction with water, and very low rates of ion migration. BaZrS3 photo-detecting devices with photo-responsivity of ~46.5 mA W -1 are also reported. The devices retain ~60% of their initial photo-response after 4 weeks in ambient conditions. Similar MAPbI3 devices degrade rapidly and show ~95% decrease in photoresponsivity in just 4 days. The findings establish the superior stability of BaZrS3 and strengthen the case for its use in optoelectronics. New possibilities for thermoelectric energy conversion using these materials are also demonstrated.

IR and UV-VIS optical spectroscopy have been used to study the transformations of the properties of diamondlike carbon films following isothermal anneals from T a ϭ300 to 650°C. Several processes due to the annealing have been observed: ͑1͒ the increase of the absorption due to vibrations of unsaturated bonds of C͑sp 2 ͒ atoms at ϳ1600 cm Ϫ1 for T a у350°C, ͑2͒ the decrease of the absorption due to C͑sp 3 ͒-H bonds at T a у350°C, and ͑3͒ the reduction of the optical energy gap. Analysis of the kinetics has shown that the dehydrogenation of the alloys and the formation of unsaturated bonds may proceed independently. The reduction of the energy gap is related to the formation of C͑sp 2 ͒ atoms with unsaturated bonding which occurs mostly in hydrogen-free regions. Intensive graphitization of the films occurs above T a ϭ650°C. Transformations of C-H bonds are proposed to occur via fast rearrangement in stressed regions leading to formation of new C͑sp 2 ͒-H bonds and formation of methane molecules as the most important product of the anneals inside the polymeric highly hydrogenated regions in the alloys. It appears that both bond removal and reordering have taken place as a result of annealing.

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We report on the incorporation of gold into silicon at a peak concentration of 1.9 × 1020 at./cm3, four orders of magnitude above the equilibrium solubility limit, using pulsed laser melting of a thin film deposited on the silicon surface. We vary the film thickness and laser process parameters (fluence, number of shots) to quantify the range of concentrations that can be achieved. Our approach achieves gold concentrations comparable to those achieved with ion implantation followed by pulsed laser melting, in a layer with high crystalline quality. This approach offers an attractive alternative to ion implantation for forming high quality, high concentration layers of transition metals like gold in silicon.

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Graphene has amazing abilities due to its unique band structure characteristics defining its enhanced electrical capabilities for a material with the highest characteristic mobility known to exist at room temperature. The high mobility of graphene occurs due to electron delocalization and weak electron-phonon interaction, making graphene an ideal material for electrical applications requiring high mobility and fast response times. In this review, we cover graphene's integration into infrared IR devices, electro-optic EO devices, and field effect transistors FETs for radio frequency RF applications. The benefits of utilizing graphene for each case are discussed, along with examples showing the current state-of-the-art solutions for these applications.Graphene has many outstanding properties due to its unique bonding and subsequently band gap characteristics, having electronic carriers act as massless DiracFermions. The material characteristics of graphene are anisotropic, having phenomenal characteristic within a single sheet and diminished material characteristics between sheet with increasing sheet number and grain boundaries. We will discuss the integration of graphene into many electronic device applications.Graphene has the highest mobility values measured in a material at room temperature, allowing integration into fast response time devices such as a high electron mobility transistor HEMT for RF applications. Graphene has shown promise in IR detectors by utilizing graphene in thermal-based detection applications.

Photoluminescence (PL) in Er-doped amorphous silicon oxycarbide (a-SiCxOy:Er) thin films, synthesized via thermal chemical vapor deposition, was investigated for carbon and oxygen concentrations in the range of 0–1.63. Intense room-temperature PL was observed at 1540 nm, with the PL intensity being dependent on the carbon and oxygen content. The strongest PL intensity was detected for a-SiC0.53O0.99:Er when pumped at 496.5 nm, with ∼20 times intensity enhancement as compared to a-SiO2:Er. Broadband excitation in the visible was observed for a-SiC0.53O0.99:Er. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses suggest that the formation of Si–C–O networks plays an important role in enhancing the Er optical activity in a-SiCxOy:Er films.