Current status and future prospects of GaN-based LEDs and LDs

We review the recent progress of GaN-based light emitting diodes (LEDs) and laser diodes (LDs) and discuss the availability for ultraviolet (UV) emission optoelectronic devices by using GaN related compound semiconductors. We fabricated UV LEDs and LDs with an emission wavelength of 365 nm which are useful for various industrial uses because of same wavelength as i-line of high-pressure mercury vapor lamps. Regarding UV LEDs, practical 365 nm UV LED with high efficiency was realized by optimizing device structure. For fabricating the ultraviolet LDs, we used the AlInGaN active layer instead of InGaN one. It was investigated that the relationship between the threshold current density and the lasing wavelength in the UV region. We demonstrated the shortest LDs with a lasing wavelength 365 nm under the continuous-wave operation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)