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Hiroto Sekiguchi

Affiliation Department of Electrical and Electronic Information Engineering
Title Associate Professor
Fields of Research Crystal growth, Semiconductor devices
Degree Ph. D. (Engineering), Sophia University
Academic Societies The Japan Society of Applied Physics, The Crystallographic Society of Japan
E-mail sekiguchi@ee
Please append ".tut.ac.jp" to the end of the address above.
Laboratory website URL http://www.int.ee.tut.ac.jp/oeg/

Research

Nitride-based light-emitting devices are attractive for realizing the full-visible and infrared emission. However, an increase in the In composition of the InGaN active layers leads to a large piezoelectric field and degraded crystal quality, and reduces the luminescence recombination. Thus, the internal quantum efficiency in a longer wavelength region remarkedly decreases. Rare-earth-doped GaN is one of the hopeful candidates as a material for realizing the red (Europium) and infrared (Erbium) nitride-based light-emitting devices. They show excellent optical properties such as a sharp line and a small wavelength shift with temperature owing to the 4f-4f transition in their inner shells. In our laboratory, the optical devices using rare-earth doped nitride semiconductor has been developed.

Theme1:Growth of rare-earth doped nitiride semiconductor

Theme2:Fabrication of red emitting-devices using Eu doped nitride semiconductor

Overview
Red LEDs using Eu doped GaN active layer

That Eu ions in nitride semiconductor exhibit strong red emission. In this research, the high efficient red emitting devices using Eu doped GaN is developed. We have succeeded the red light-emitting diode using a PN junction of the nitride semiconductor and Eu doped GaN active layer. To realize the higher efficient optical devices, optimization of device structure and development of a novel crystal growth technology are been proceeding.

Research Achievement
◇ Hiroto Sekiguchi, Yasufumi Takagi, Tatsuki Otani, Ryota Matsumura, Hiroshi Okada, and Akihiro Wakahara, “Red Light-Emitting Diodes with Site Selective GaN:Eu Active Layer”, Japanese Journal of Applied Physics 52 (2013) .
◇ Akihiro Wakahara, Hiroto Sekiguchi, Hiroshi Okada, and Yasufumi Takagi, “Current status for light-emitting diode with Eu-doped GaN active layer grown by MBE”, Journal of Luminescence 132 (2012) 3113.


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