Dilute GaAsN layers are grown by liquid phase epitaxy from saturated melts containing polycrystalline GaN as the source of nitrogen. From photoluminescence measurements the nitrogen content in the material is obtained. Low temperature photocurrent and photocapacitance measurements reveal the presence of an electron trap with an ionization energy of 0.65-0.67 eV in the as-grown layers, whose origin is related to interstitial (N-N) As defects. High temperature annealing of the material almost removed the trap and new electron traps at 0.8 and 0.9 eV are produced. It is suggested that during the annealing process the (N-N) As defects, due to their lower energy of formation, are converted to more thermally stable (As Ga -N As ) or (AsN) As defects which might be the source of the new electron traps. High temperature treatment of the growth melt with erbium is found to remove nitrogen from the grown layer with complete annihilation of all the electron traps.

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The main aim of the study is to perform the long-term stability test of gain of the single mask triple GEM detector. A simple method is used for this longterm stability test using a radioactive X-ray source with high activity. The test is continued till accumulation of charge per unit area > 12.0 mC/mm 2 . The details of the chamber fabrication, the test set-up, the method of measurement and the test results are presented in this paper.

Understanding defects, disorder and doping due to N implantation in ZnO is one of the most debated issues for the last few years. In the present work, a comprehensive investigation has been carried out using Raman, photoluminescence (PL) spectroscopy and grazing‐incidence X‐ray diffraction on 50 keV N ions implanted granular ZnO with different fluence (approximately up to 6.5% atomic concentration) along with postimplantation annealing. Raman investigation suggests that 275, 510, 643, and 857 cm−1 modes are directly related to nitrogen. Additionally, VZn may have some role in stabilizing 275 cm−1 mode. The broadening (or tailing) of E2low mode is related to vibration of distorted Zn sublattice, which may be a product of ion implantation generated defect cluster like VZn–VO. The distortion starts to reduce with annealing at elevated temperatures. Direct correlation between 555 cm−1 Raman mode and the tailing of E2low mode has been found. More defect clustering is vivid from the reduced PL of the ZnO samples with increasing implantation fluence. So, tailing of E2low Raman mode, increasing intensity of 555 cm−1 mode and nonradiative defect centers are of common origin. Both the ratios E1(2LO)/E1(LO) and E2high/E1(LO) can be used as parameters to measure the defective nature of ZnO after ion implantation/irradiation. Low temperature PL (selected samples) suggests absence of shallow acceptor states, although negative thermal quenching above 175 K has been observed (implantation fluence 1 × 1016 ions/cm2 and annealed at 500°C) which can be a signature of deep acceptors.

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