The origin of bimodal luminescence of beta-SiAlON:Eu2+ phosphors as revealed by fluorescence microscopy and cathodoluminescence analysis

<span lang="EN-US" style="font-family: &quot;Calibri&quot;,&quot;sans-serif&quot;; font-size: 10.5pt; mso-bidi-font-size: 11.0pt; mso-ascii-theme-font: minor-latin; mso-fareast-font-family: 宋体; mso-fareast-theme-font: minor-fareast; mso-hansi-theme-font: minor-latin; mso-bidi-font-family: &quot;Times New Roman&quot;; mso-bidi-theme-font: minor-bidi; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA;"><font color="#000000">Eu2+-doped SiAlON phosphors with the composition of EuxSi6-zAlzOzN8-z(0.5 &lt;= z &lt;= 3) at a fixed x = 0.01 were synthesized by the gas pressure sintering method. Dependence of luminescence properties on the phase compositions in beta-SiAlON:Eu2+ phosphors has been examined via fluorescence microscope and scanning electron microscope equipped with a cathodoluminescence spectrometer and an energy dispersive spectrometer. Bimodal emission (green and violet) from beta-SiAlON phase is observed in the samples with z &gt;= 2, indicating co-existence of two different kinds of coordination for Eu2+ ions in the host lattice. (C) 2013 Elsevier Ltd. All rights reserved.</font></span

Enhancement of photoluminescence intensity of GaInNAs/GaAs quantum wells by two-step rapid thermal annealing

We investigate the effect of rapid thermal annealing on InGaNAs/GaAs quantum wells. At optimized annealing temperatures and times, the greatest enhancement of the photoluminescence intensity is obtained by a special two-step annealing process. To identify the mechanism affecting the material quality during the rapid thermal annealing, differential temperature analysis is applied, and temperature- and power-dependent photoluminescence is carried out on the samples annealed under different conditions. Our experiment reveals that some composition redistribution or other related ordering process may occur in the quantum-well layer during annealing. Annealing at a lower temperature for a long time primarily can remove defects and dislocations while annealing at a higher temperature for a short time primarily homogenizes the composition in the quantum wells

Growth and Characterization of GaSb-Based Type-II InAs/GaSb Superlattice Photodiodes for Mid-Infrared Detection

InAs/GaSb superlattice (SL) midwave infrared photovoltaic detectors are grown by molecular beam epitaxy on GaSb(001) residual p-type substrates. A thick GaSb layer is grown under the optimized growth condition as a buffer layer. The detectors containing a 320-period 8ML/8ML InAs/GaSb SL active layer are fabricated with a series pixel area using anode sulfide passivation. Corresponding to 50% cutoff wavelengths of 5.0 mu m at 77 K, the peak directivity of the detectors is 1.6 x 10(10) cm.Hz(1/2) W-1 at 77 K