Applied Physics

True-Blue Laser Diodes

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Science  21 Jan 2000:
Vol. 287, Issue 5452, pp. 393
DOI: 10.1126/science.287.5452.393e

Laser diodes based on the wide gap III-V compounds of indium gallium nitride (InGaN) have been demonstrated to operate at room temperature for thousands of hours at wavelengths in the violet range (390 to 420 nm). For applications in full-color laser displays, laser operation in the blue (450 nm) is desirable, but the required reduction in effective band gap obtained by increasing the amount of indium results in a prohibitive increase in the current density required to initiate and maintain lasing. These high currents result in catastrophic failure of a multiple quantum well device after only a few hours of operation. Nakamura et al. now show that by careful design of the laser cavity, and in particular the number of InGaN wells that make up the active region of the laser, they can reduce the threshold current and extend the lifetime of the devices to approximately 200 hours. The authors suggest that reverting to a single quantum well structure helps to preserve the integrity of a InGaN layer containing higher levels of indium.—ISO

Appl. Phys. Lett.76, 22 (2000).

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