Ikuo Suemune, Yujiro Hayashi, Shuhei Kuramitsu, Kazunori Tanaka, Tatsushi Akazaki, Hirotaka Sasakura, Ryotaro Inoue, Hideaki Takayanagi, Yasuhiro Asano, Eiichi Hanamura, Satoru Odashima, Hidekazu Kumano
APPLIED PHYSICS EXPRESS 3 5 054001.1-054001.3 2010年
[査読有り][通常論文] A light-emitting diode (LED) in the optical-fiber communication band showed special features after replacing the n-type electrode with niobium (Nb) superconducting metal. Nb electrodes prepared on an InGaAs-based semiconductor surface formed a superconductor/semiconductor/superconductor junction, and the current-voltage characteristics exhibited both DC and AC Josephson junction properties. This was a result of the injection of electron Cooper-pairs into the n-InGaAs active layer of an LED. The drastic enhancement of the electroluminescence output observed below the Nb superconducting critical temperature, T(c), demonstrates the active role of electron Cooper-pairs in radiative recombination. Lifetime measurements of this LED and accurate evaluation of the luminescence output made it possible to estimate the radiative recombination lifetimes. A theoretical formula derived for the Cooper-pair radiative recombination accurately describes both the measured steep reduction of the radiative recombination lifetime and the observed enhancement of the internal quantum efficiency below Tc. This work will assist the development of interdisciplinary physics and new applications in superconductivity and optoelectronics. (C) 2010 The Japan Society of Applied Physics