Nichia’s Green Laser Diode Reaches 515 Nm
The Japanese GaN pioneer did not provide reliability data for the 515 nm devices, but it also produced 510–513 nm diodes that operate for 500 hours without a change in their electrical characteristics. Beyond 500 hours the lasers’ performance steadily degraded. The Nichia researchers estimated their overall lifetime – which is defined as ending when operating current increases by 30% from its initial value – to be 5000 hours.
In an Applied Physics Express paper published on May 22, the team developing the lasers reported a separate confinement heterostructure diode “almost the same as" a design dating back to 2001. Optimized MOCVD processes are critical to producing the high-indium-content material required to access green wavelengths on a free- standing c-plane GaN substrate.
“We improved the growth condition of epitaxial layers," the Nichia team wrote. “The crystal quality was improved even in indium- rich InGaN active layers."