The role of ITO resistivity on current spreading and leakage in InGaN/GaN light emitting diodes

The effect of a transparent ITO current spreading layer on electrical and light output properties of blue InGaN/GaN light emitting diodes (LEDs) is discussed. When finite conductivity of ITO is taken into account, unlike in previous models, the topology of LED die and contacts are shown to significantly affect current spreading and light output characteristics in top emitting devices. We propose an approach for calculating the current transfer length describing current spreading. We show that an inter-digitated electrode configuration with distance between the contact pad and the edge of p-n junction equal to transfer length in the current spreading ITO layer allows one to increase the optical area of LED chip, as compared to the physical area of the die, light output power, and therefore, the LED efficiency for a given current density. A detailed study of unpassivated LEDs also shows that current transfer lengths longer than the distance between the contact pad and the edge of p-n junction leads to increasing surface leakage that can only be remedied with proper passivation. © 2017 Elsevier Lt

Quantum back-action limits in dispersively measured Bose-Einstein condensates

Back-action limited measurements of many-body quantum systems are a challenging topic of relevance to open quantum systems and quantum metrology. This work makes important contributions in that direction by experimentally measuring and theoretically modeling via a quantum-trajectories approach coherence in an atomic Bose-Einstein condensate coupled to a far-off-resonant laser beam

Apheresis training in Turkey.

Continuing education and standardization are of utmost importance in apheresis science as every field in medicine. Especially, the last 5 years witnessed remarkable progress in apheresis science in Turkey, both in terms of increased numbers of therapeutic apheresis centers, therapeutic apheresis procedures performed per year, and also in terms of quality and standardization. This brief report summarizes the current status of apheresis training in Turkey and milestones of its development