| Budget Amount *help |
¥18,330,000 (Direct Cost: ¥14,100,000、Indirect Cost: ¥4,230,000)
Fiscal Year 2016: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2015: ¥6,110,000 (Direct Cost: ¥4,700,000、Indirect Cost: ¥1,410,000)
Fiscal Year 2014: ¥7,410,000 (Direct Cost: ¥5,700,000、Indirect Cost: ¥1,710,000)
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| Outline of Final Research Achievements |
A long fast-component photoluminescence lifetime of 2.07 ns at room temperature was obtained for the near-band-edge emission in an m-plane freestanding GaN crystal grown by hydride vapor phase epitaxy on a bulk GaN seed wafer synthesized by the ammonothermal method using an acidic mineralizer. Omnidirectional photoluminescence (ODPL) measurement was proposed to absolutely quantify the quantum efficiency of radiation (g) in crystals. A methodology for quantifying internal quantum efficiency from such experimentally obtained g is derived. A strategy for increasing the square of an overlap integral of electron and hole wavefunctions in polar c-plane AlGaN multiple quantum wells (MQWs) is proposed. By applying quadratic modulation to AlN mole fractions along the c-axis, local bandgap energies and concentrations of immobile charges induced by polarization discontinuity are simultaneously controlled throughout the MQW structure, and optimized band profiles are eventually achieved.
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