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A new detector for PET using multi-pixel photon counters (MPPCs) was developed for MRI compatible applications. This module has an 8 × 8 MPPC array, each segment has a 3 mm × 3 mm active area, and the pitch of the array is 4.1 mm in both directions. A temperature sensor is attached to the back of the array for temperature compensation. The MPPC array is connected to the front-end circuit with a detachable...
Currently, GaN white LEDs exhibit luminous efficacy greater than 150 lm/Watt, and external quantum effiencies higher than 50% at low drive currents. However, current commercial LEDs grown on the c-plane of the wurtzite crystal suffer from the quantum confined Stark effect (QCSE) due to the large polarization-related electric fields. This effect causes band bending in the active region and results...
It has been several years since InGaN/GaN light-emitting diodes (LEDs) on nonpolar and semipolar orientations were first demonstrated. Prominent performance and inherent potential of these crystallographic orientations have been revealed as bulk-GaN substrates of arbitrary orientations became available for epitaxial device growth. At this point in time, we intend to survey the progress made to date...
Summary form only given. Charge separation due to spontaneous and piezoelectric polarization inherent to the wurtzite structure has deleterious effects on the performance of most c-axis oriented devices. To overcome this problem, Nonpolar GaN, such as a-plain and m-plain GaN or semipolar GaN substrates have been grown. We reported the fabrication of violet InGaN/GaN Light Emitting Diodes (LEDs) on...
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