Exploring optoelectronic nanostructures for the enhancement and inhibitation of luminescence

2017 Fiscal Year Final Research Report

• Project/Area Number: 26706003
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Nanostructural physics
• Research Institution: Tohoku University
• Principal Investigator: Kojima Kazunobu 東北大学, 多元物質科学研究所, 准教授 (30534250)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 発光増強 / 半導体光物性 / 窒化物半導体 / 量子効率

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.

Free Research Field

半導体光物性