ELECTROCHEMICAL SULFUR PASSIVATION OF VISIBLE (SIMILAR-TO-670 NM) ALGAINP LASERS

III-V based devices such as field effect transistors, heterojunction bipolar transistors, and lasers often have surface leakage and thermal degradation problems due to surface states which pin the Fermi level to the midgap. Sulfur based passivation processes are known to improve device performance by altering surface-state densities. We have developed a voltage-controlled anodic sulfur passivation scheme using Na2S dissolved in ethylene glycol. Our process has repeatedly produced a approximately 25% improvement in peak output power near the catastrophic damage limit in visible (lambda = 670 rum) AlGaInP edge-emitting lasers. The threshold current density before and after passivation, and the I-V characteristics before and after catastrophic failure, were essentially unchanged indicating that passivation raises the threshold for facet damage.