HexaTech Inc of Morrisville,NC,USA has reported the results of an ongoing collaboration with development partner Tokuyama Corp of Tokyo,Japan that has demonstrated UV-C LEDs with exceptional output power and improvements in internal quantum efficiency(IQE).HexaTech reckons that the results raise the bar to what is possible with the technology,and enable commercially available high-performance,high-reliability UV-C LEDs.
HexaTech was spun off from the Department of Materials Science of North Carolina State University in 2001 to produce single-crystal aluminium nitride(AlN)substrates for both electronic and optoelectronic devices.AlN substrate material can enable long-life UV-C LEDs for disinfection applications,as well as deep UV lasers for biological threat detection and high-voltage power semiconductors for smart grid and efficient power conversion.The firm's existing product lines include single-crystal and polycrystalline AlN substrates(although long-life UV-C LEDs and high-voltage power devices based on AlN substrates are also in development).
HexaTech says that,since their inception,UV-C LEDs have held the promise of a compact,highly efficient,long-life light source for sterilization and purification applications.The rapidly accelerating interest in LEDs for disinfection applications operating at UV-C wavelengths requires a solution with high output power,high efficiency and long lifetimes,says the firm.However,most commercially available UV-C LED products currently struggle with limited output power,efficiency and device lifetimes.A key requirement for improving these limitations is to reduce the device defect density,for which IQE is a key measure and is critically related to the underlying bulk material quality.
"As HexaTech's own device development has shown,using our high-quality,low-dislocation material,we are able to produce UV-C LEDs with record-setting reliability and lifetimes,exceeding more than 600 hours of accelerated testing,with virtually no degradation,"says HexaTech's director of device development Dr Baxter Moody.
Now,by coupling HexaTech's low-dislocation-density bulk aluminum nitride(AlN)substrates with Tokuyama's hydride vapor phase epitaxy(HVPE)and device fabrication,Tokuyama was able to produce UV-C LEDs with over 25mW of output power at 265nm,and internal quantum efficiencies greater than 70%.
"This collaboration demonstrates that,when combining HexaTech's market-leading bulk substrate quality,with Tokuyama's high-quality HVPE and excellent device fabrication,breakthrough,record-setting results are possible,"says HexaTech's CEO Joe Grzyb.
"Working together with HexaTech and their substrates,Tokuyama has made great improvements in the performance of our UV-C LEDs,accelerating the process for their commercial availability,"comments Tokuyama's chief research engineer Toru Kinoshita.
