Effect of active-layer structures on temperature characteristics of InGaN blue laser diodes

We investigate temperature characteristics of 445-nm-emitting InGaN blue laser diodes (LDs) with several types of active-layer structures. The double quantum-well (QW) LD structures having an n-type doped barrier show negative or very high characteristic temperature depending on the barrier In composition. On the contrary, the double QW structures having an undoped barrier and the single QW structure show normal temperature dependence of LD characteristics. From the simulation of carrier density and optical gain, it is found that the anomalous temperature characteristics of blue LDs are closed related to the inhomogeneous hole distribution between QWs due to the low hole mobility of InGaN materials.