Degradation behavior of LED by irradiation

LEDの線による照射劣化挙動

武内 伴照   ; 柴田 裕司 ; 大塚 紀彰 ; 上原 聡明; 熊原 肇*; 土谷 邦彦 

Takeuchi, Tomoaki; Shibata, Hiroshi; Otsuka, Noriaki; Uehara, Toshiaki; Kumahara, Hajime*; Tsuchiya, Kunihiko

水中でも伝送可能かつ耐放射線性をもつ可視光無線伝送システムの構築を目指して、発光波長がほぼ同じで比較的光量の大きい異なった2種類のLEDを選定し、その線照射効果を調べた。照射劣化を評価するため、照射前後におけるLEDの電流電圧特性や全光束を測定した結果、照射後に全光束が減少するとともに樹脂レンズ部が着色したが、電流電圧特性はほとんど変化は無かった。このことから、両素子の特性劣化の主因は半導体部分の劣化ではなく、樹脂の着色によるものであることが示唆された。一方、試験した内の1種類のLEDについて、照射量に対する全光束の減少速度が小さかったことから、開発中の無線伝送システムの発光素子に適すると考えられることが分かった。

irradiation effects on LEDs which were fabricated by different two fabricators and had relatively large amount of light were evaluated toward the development of a radiation-resistant in-water wireless transmission system using visible light. The current-voltage characteristics and total luminous flux of the LEDs were measured before and after the irradiation. After the irradiation, the total luminous flux decreased and the resin lenses turned oxblood. Meanwhile, the current-voltage characteristics hardly changed. These results indicated that the decreases of the total luminous flux of the LEDs were mainly caused by not the degradation of the semiconductor parts but the coloring of the resin parts by the irradiation. On the other hand, the decrease rates of the total lumious fluxes with absorbed dose of the LEDs fabricated one fabricator were smaller than the others. Therefore, they are possible candidates for the light emitting devices of the developing in-water transmission system.