Attack the green region successfully developed 515 Nichia nm laser diode

The Japanese LED maker Nichia (Nichia) using GaN substrate manufacturing blue laser, with improvement of process and structure, produce a wavelength of 515 nm continuous wave laser diode, breaking the previous electrically excited indium gallium nitride (InGaN) laser maintained the longest wavelength 500 nm record, and is in the life cycle of hundreds of hours of goal.

A leading position in the GaN series of Nichia, the reliability of the data did not provide a 515 nm laser, but the other money they make for the laser diode wavelength 510-513 nm can operate 500 hours in electrical unchanged; more than 500 hours after the laser efficiency will be gradually reduced. According to the operating current of the Nichia increased by 30% compared with the initial value to define the useful life of the laser, it is estimated that the laser can be used for up to 5000 hours.

The Nichia team uses a laser diode to produce lasers that separate the confined heterostructure (separate, confinement, SCH), which is almost exactly the same as they were published in 2001. By optimizing the MOCVD process, the deposition of AlInGaN thin film on C (free-standing) GaN (C-plane) substrate is the key to the high content of indium to produce green light.

The Nichia team said that they improve the epitaxial layer, especially multi quantum well layer (MQW) of the growth conditions, but also improve the high indium content InGaN activated crystalline quality layer, but did not further comment about the optimization condition of details. Nichia has also previously published a 488 nm wavelength InGaN laser diode, but the poor quality of the crystal led to the formation of the non radiative region, in the photoluminescence (photoluminescence, PL) analysis of the dark zone. Nichia Takashi Mukai et al. Point out that these areas have been eliminated in the design of new devices.

At room temperature, the threshold values of current and current density of 515 nm laser diode at wavelength of 53 mA and 4.4 kA/cm2. Under the operating current of 88 mA, voltage of 5.5 V, the output power is 5 mW. While the wavelength of 510 - 513 nm laser diode, at room temperature due to temperature changes caused by the wavelength shift of the maximum value of 0.022 nm/K, far less than OSRAM and Rohm recently introduced green laser diode.