Room-temperature operation of GaN-based blue-violet laser diodes fabricated on sapphire substrates using high-temperature-grown single-crystal AlN buffer layers

The laser operation has been demonstrated for the first time for the test devices fabricated on GaN layers grown on sapphire substrates by metalorganic chemical vapor deposition using high-temperature-grown single-crystal AlN buffer layers (HT-AlN buffer layers). The device structure was the simple electrode-stripe type with a 1-mm-long and 10-μm-wide laser cavity. The wavelength was 413 nm. The threshold current and current density were 760 mA and 7.6 kA/cm 2 , respectively. The operation voltage at the threshold current was 8 V. These characteristics were comparable to one of the best values reported using conventional low-temperature grown buffer layers, considering the used simple device structure. This fact was thought to support the promising potential of the HT-AlN buffer to realize high performance practical devices on sapphire substrates.