Temporal Emission Characteristics of Light Emitting-Diodes for High-Speed Pulsed Current

Abstract

Temporal emission characteristics of light emitting diodes (LEDs) for high-speed repetitive current have been investigated. For this purpose, three commercially available LEDs (red, green and blue LEDs) were prepared. Each LED was driven by a specially designed pulse generator constructed using an avalanche transistor to generate high-speed pulse current. Resultant injection current showed a nanosecond duration pulse with peak height of a few amperes. Time responses and spectral profiles of the emission waveforms were measured with respect to the pulsed current. Resultant light durations of the pulsed LEDs were in the nanosecond range. When the injection current increased, the peak emission intensity of the LED increased without saturation. In particular, the ultraviolet component of the blue LED became evident, resulting in peak emission intensity of 30 mW with duration of 5 ns. Lifetime of the pulse-operated LED was over 1O" shots, which corresponds to 140 hours running at repetition frequency of 20 kHz. KEYWORDS: light-emitting diode, nanosecond light source, ultraviolet light, avalanche transistor 1.‚Í ‚ ¶‚ß ‚É "-OEõƒ_ƒCƒI •[ ƒh(LED)‚Í •‚ '¬ "¹ ˜H ‚Ì "d OEõ OEfŽ¦ "‚⠕AE-¾,OEõ 'Ê •M'• 'u ‚È ‚Ç‚ÉŽg‚í ‚ê,"ü-Í •M• † ‚É'Î ‚· ‚é ‰ž "š ‚ª '¬ ‚¢,Žõ-½‚ª "¼‰i ‹v "I ‚Å‚ ‚é ‚È ‚Ç‚Ì "Á'· ‚ª ‚ ‚é."Á ‚É ‰ž "š •« ‚ɂ‚¢ ‚Ä‚Í "K•Ø‚È'f Žq ‚AE ‹ì "®‰ñ˜H®‰ñ˜H ‚ð-p ‚¢ ‚ê ‚Î ƒi ƒm •b ƒI•[ ƒ_•[ ‚Ì ƒp ƒ‹ ƒX OEõ‚ð "-• ¶ ‚³ ‚¹ ‚é ‚± ‚AE ‚ª ‚Å‚« ‚é.ƒp ƒ‹ ƒX OEõOE¹‚AE ‚µ‚Ä‚Ì-˜-p‚ð•l ‚¦ ‚½•ê • ‡,•u Žž"I ‚É'å ‚« ‚È•ú ŽË'©‚ª-v ‹• ‚³ ‚ê ‚é‚ª,ƒp ƒ‹ ƒX •• ‚ð'Z ‚-‚· ‚é ‚± ‚AE‚É ‚ae ‚蕽‹Ï '• "ü "d-¬ ‚ª OE¸•-‚· ‚é ‚½‚ß,•Å 'å 'è Ši ‚ð '´ ‚¦ ‚é"d-¬ 'l ‚Å ‚àLED‚ð "M '¹ •• ‚³ ‚¹ ‚é ‚± ‚AE‚È ‚-‹ì "®‚Å‚« ‚é.ƒJ ƒ^ƒ• ƒO ‚â Žd-l•' ‹L•Ú‚Ì •" • § ‰ñ˜H‚ł͉ñ˜H‚Å‚Í,ƒp ƒ‹ ƒX ‹ì "®‚AE‚µ‚Ä'è Ši "d-¬ ‚Ì •‚ •X•" "{‚© ‚ç10"{ ‚Ì "d-¬ ‚ª '• "ü ‚³ ‚ê ‚Ä‚¢ ‚é.‚± ‚ê ‚É'Î ‚µ‚Ä‰ä •X‚Í,Žs "Ì ‚Ì •Â•FLED‚É 'è Ši "d-¬ ‚Ì100"{ ˆÈ•ã ‚Ì ƒs•[ ƒN "d-¬ ‚ð '• "ü ‚µ ‚ăp ƒ‹ ƒX ‹ì "® ‚µ,Ž ‡ ŠO•ü ƒp ƒ‹ ƒXOEõ‚ð"¾‚é•û-@‚ð•ñ •• ‚µ‚½1'2).‚µ ‚© ‚µ ‚» ‚Ì '¼‚ÌLED‚É 'Î ‚µ ‚Ä ‚Í 'å "d-¬ ƒpƒ‹ ƒX‹ì "®‚É'Î ‚· ‚鉞 "š •«,'Ï ‹v •«,•ú ŽË'©‚È ‚Ç‚ð'è-Ê "I ‚É•\ ‚µ‚½•ñ •• ‚ª ‚Ù ‚AE ‚ñ ‚Ç-³ ‚¢.