In Situ Monitoring of Pulsed Laser Annealing of Eu-Doped Oxide Thin Films.

Eu3+-doped oxide thin films possess a great potential for several emerging applications in optics, optoelectronics, and sensors. The applications demand maximizing Eu3+ photoluminescence response. Eu-doped ZnO, TiO2, and Lu2O3 thin films were deposited by Pulsed Laser Deposition (PLD). Pulsed UV Laser Annealing (PLA) was utilized to modify the properties of the films. In situ monitoring of the evolution of optical properties (photoluminescence and transmittance) at PLA was realized to optimize efficiently PLA conditions. The changes in optical properties were related to structural, microstructural, and surface properties characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The substantial increase of Eu3+ emission was observed for all annealed materials. PLA induces crystallization of TiO2 and Lu2O3 amorphous matrix, while in the case of already nanocrystalline ZnO, rather surface smoothening0related grains' coalescence was observed.

Phthalocyanine Photoregeneration for Low Power Consumption Chemiresistors.

It is well-known that the applicability of phthalocyanine chemiresistors suffers from long recovery time after NO2 exposure. This circumstance enforces the necessity to operate the sensors at elevated temperatures (150-200 °C), which shortens the sensor lifetime and increases its power consumption (regardless, a typical measurement period is longer than 15 min). In this paper, we propose a new method for fast and effective recovery by UV-vis illumination at a low temperature (55 °C). The method is based on short illumination following short NO2 exposure. To support and optimize the method, we investigated the effects of light in the wavelength and intensity ranges of 375-850 nm and 0.2-0.8 mW/mm2, respectively, on the rate of NO2 desorption from the phthalocyanine sensitive layer during the recovery period. This investigation was carried out for a set of phthalocyanine materials (ZnPc, CuPc, H2Pc, PbPc, and FePc) operating at slightly elevated temperatures (55-100 °C) and was further supported by the analysis of UV-vis and FTIR spectral changes. We found out that the light with the wavelength shorter than 550 nm significantly accelerates the NO2 desorption from ZnPc, CuPc, and FePc, and allows bringing the measurement period under 2 min and decreasing the sensor power consumption by 75%. Possible mechanisms of the light-stimulated desorption are discussed.