Investigation into the Anomalous Temperature Characteristics of InGaN Double Quantum Well Blue Laser Diodes Using Numerical Simulation

Abstract

GaN-based blue laser diodes (LDs) may exhibit anomalous temperature characteristics such as a very high characteristic temperature (T 0) or even negative T 0. In this work, temperature-dependent characteristics of GaN-based blue LDs with InGaN double quantum well (QW) structures were investigated using numerical simulations. The temperature-dependent threshold current is found to become increasingly anomalous as the thickness or doping concentration of the barrier layer between QWs increases. For a properly chosen barrier thickness and doping concentration, very high T 0 of >10,000 K can be obtained. The anomalous temperature characteristics of these InGaN blue LDs are attributed to the increase of gain at the n-side QW with increasing temperature because of the thermally enhanced hole transport from the p-side to the n-side QW.

Investigation of the Optimum Mg Doping Concentration in p-Type-Doped Layers of InGaN Blue Laser Diode Structures

“…Using the refractive index data of GaN, AlGaN, and InGaN alloys at 450 nm from Refs. [25,[43][44][45], the refractive indices of the GaN layer, Al 0.04 GaN cladding layers, and In 0.02 GaN waveguides were chosen to be 2.48, 2.46, and 2.50, respectively. Figure 1b shows the profiles of the refractive index and wave intensity of the lasing mode as a function of the vertical position when the thicknesses of both the LWG and UWG are 120 nm, and the Al composition of the EBL is 20%.…”

“…However, the effect of SRH recombination on the threshold current was found to be almost negligible when the SRH lifetime was longer than 10 ns. The lasing threshold of the InGaN blue LDs is strongly influenced by the Auger recombination coefficient (C) [18,45]. In the current simulations, C was chosen to be 2 × 10 30 cm −6 /s for the simulated blue LD to exhibit a J th of ~1 kA/cm 2 .…”