Point defects in high-purity GaN layers grown by hydride vapor phase epitaxy are studied by steady-state and time-resolved photoluminescence (PL). The electron-capture coefficients for defects responsible for the dominant defect-related PL bands in this material are found. The capture coefficients for all the defects, except for the green luminescence (GL1) band, are independent of temperature. The electron-capture coefficient for the GL1 band significantly changes with temperature because the GL1 band is caused by an internal transition in the related defect, involving an excited state acting as a giant trap for electrons. By using the determined electron-capture coefficients, the concentration of free electrons can be found at different temperatures by a contactless method. A new classification system is suggested for defect-related PL bands in undoped GaN.

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For the last decade, optically transparent antennas have been a topic of research for applications ranging from satellite communication to window embedded telecommunications. The most common material used for transparent antennas has so far been Indium Tin Oxide (ITO). However, the long term availability of indium due to worldwide shortages and increasing prices is of great concern, necessitating the exploration of replacement materials. Among the most promising candidates is zinc oxide heavily doped with gallium (GZO), which can be produced in the form of thin films with conductivity comparable to that of ITO. In order to study the efficacy of GZO transparent antennas, a printed planar‐dipole antenna was designed and fabricated. The antenna operated in the 2.4 GHZ Industry science and measurement (ISM) band with a return loss of approximately 13 dB. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:773–777, 2017

Hot-electron energy relaxation time is deduced for Ga-doped ZnO epitaxial layers from pulsed hot-electron noise measurements at room temperature. The relaxation time increases from ∼0.17 ps to ∼1.8 ps when the electron density increases from 1.4 × 1017 cm−3 to 1.3 × 1020 cm−3. A local minimum is resolved near an electron density of 1.4 × 1019 cm−3. The longest energy relaxation time (1.8 ps), observed at the highest electron density, is in good agreement with the published values obtained by optical time-resolved luminescence and absorption experiments. Monte Carlo simulations provide a qualitative interpretation of our observations if hot-phonon accumulation is taken into account. The local minimum of the electron energy relaxation time is explained by the ultrafast plasmon-assisted decay of hot phonons in the vicinity of the plasmon–LO-phonon resonance.