Thermal analysis of InGaN/GaN (GaN substrate) laser diodes using transient interferometric mapping
Transient thermal behaviour and current distribution is investigated in InGaN/GaN blue lasers grown on GaN substrate. Back side transient interferometric mapping (TIM) method was applied for probing the temperature-induced phase shift due to increase in refractive index in the GaN laser ridge. The laser operates in a pulsed mode with pulse duration in the time scale from 300 ns to 2 μs. By using 2D thermal modeling, the comparison of the experimental and simulated phase shift allows to estimate a maximal temperature in the active region. The thermal mapping along the ridge reveals the inhomogeneity in the current flow attributed to substrate dopant distribution.
Fig. 1. Temperature distributions along the depth of the laser structure, as a function of time.
Source: Microelectronics Reliability