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Up-converted photoluminescence of GaN nanowires is observed at the temperature above 375 K. At 475 K, the mechanism of the photoluminescence was identified as phonon-assisted bandtail emission. Such a phenomenon contributes to optical refrigeration.
Laser cooling of solids based on anti-Stokes photoluminescence was proposed in 1929 [1]. Indeed, through the light emission based on phonon-assisted anti-Stokes photoluminescence, the average photon energy emitted is larger than that for the absorbed pump photons. The difference between the emitted and absorbed photon energies is made up by the energy of each removed phonon. Since phonons represent...
Anti-Stokes photoluminescence (ASPL) of n-type GaN is observed at room temperature. By studying behaviors of ASPL, the mechanism is identified as phonon-assisted bandtail photoluminescence. Such a process results in laser cooling.
A multiphysics finite element method (FEM) based software, COMSOLtrade has been used to simulate coupled electromagnetic shielding and thermal stress issues for system-in-package (SiP) modules. The ceramic and silicon carriers under study have embedded shielding ground planes. Power HEMT RF devices in GaAs technologies are embedded on and within the carrier causing local thermal hotspots. Thermal...
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