Ultraviolet laser diodes with AlGaN and InAlGaN multiple-quantum-well active regions
We will report on the design and performance characteristics of AlGaN and InAlGaN multiple-quantum-well (MQW) laser diodes emitting in the ultraviolet spectral region. The nitride laser diodes were grown on (0001) c-plane sapphire substrates by metal organic chemical vapor deposition. Under pulsed bias conditions, laser operation was obtained in gain-guided laser devices with uncoated mirror facets and cavity length ranging from 300 to 1500 mm. For laser diodes with AlGaN MQW active regions room-temperature threshold current densities as low as 23 kA/cm2 have been achieved with emission wavelengths between 361.6 nm and 358.5 nm. This is the shortest emission wavelength yet reported for a semiconductor laser diode. The maximum output power for AlGaN MQW laser diodes was 45 mW per facet with differential quantum efficiencies of 1.3%. Slightly improved performance has been obtained for laser diodes with InAlGaN MQW active regions. The indium composition in the quantum wells was ranging from 0.5% to 3% and the aluminum content was varying between 2% and 4%. Pulsed laser operation has been obtained with threshold current densities between 13 and 18 kA/cm2, with emission wavelength ranging between 362.4 nm and 359.9 nm. Light output powers greater than 80mW under pulsed current-injection conditions and differential quantum efficiencies of 4.2% have been achieved. Finally, growth of UV laser diode heterostructures on low dislocation density substrates, like GaN or AlN, will be discussed.
Kneissl, M. A. Ultraviolet laser diodes with AlGaN and InAlGaN multiple-quantum-well active regions (Invited Talk). MRS Fall Meeting 2003, Boston; 2003 December 1-5; Boston; MA