Study of GaN-based Laser Diodes in Near Ultraviolet Region

Abstract

Ultraviolet (UV) laser diodes (LDs) were grown on epitaxially laterally overgrown GaN substrates by a metalorganic chemical vapor deposition method. We fabricated three types of UV LDs whose active layers were (I) ternary InGaN, (II) quaternary AlInGaN and (III) binary GaN single quantum well (SQW) structures. We investigated the LD characteristics in detail in the near UV region. LDs whose active layers were quaternary Al0.03In0.02Ga0.95N were demonstrated under the pulsed-current-biased conditions at room temperature. The emission wavelength of these LDs was the shortest wavelength (366.4 nm) in our experiments. We also demonstrated binary GaN SQW LDs for the first time. The threshold current density, voltage and emission wavelength of these LDs under 25°C continuous-wave (cw) operation were 3.5 kA/cm2, 4.6 V and 369.0 nm, respectively. The estimated lifetime was approximately 2000 h under 25°C cw operation at an output power of 2 mW.