Improving Performance of GaAs-Based Vertical-Cavity Surface-Emitting Lasers by Employing Thermally Conductive Metal Substrate

We investigated the effect of the conducting substrate on the performance of GaAs-based VCSELs, where the substrates were 230 μ m-GaAs (reference), 10 μ m-GaAs/metal, and 0.5 μ m-GaAs/metal. The VCSELs with the 10 μ m- and 0.5 μ m thick GaAs/metal-substrates produced higher light output power than the reference. For example, the thin GaAs/metal substrate samples showed 16.3%–16.7% higher light output power at 3.0 A than the reference. It was shown that the thin GaAs samples produced 12.2%–14.0% higher power conversion efficiency at 3.0 A than the reference. At a high current region, the metal-substrate samples yielded lower junction temperature than the reference, namely, the thin GaAs samples gave 42 °C–47.4 °C lower junction temperature at 2.0 A than the reference. Further, the thin GaAs samples revealed better light output degradation characteristics than the reference. For instance, the light output of the reference was degraded by 30.2% at 85 °C, whereas the thin GaAs samples were degraded by 20.1%–20.5%. Near-field images and emission profiles demonstrated that the metal-substrate samples suffered from no damage incurred during the VCSEL fabrication process.