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 μm-GaAs (reference), 10 μm-GaAs/metal, and 0.5 μm-GaAs/metal. The VCSELs with the 10 μm- and 0.5 μm 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.