Failure analysis of 850 nm proton-implanted VCSELs

VCSELs are increasingly being adopted for use in data communications products, with numerous other applications being explored. Their low threshold current, circular beam, and excellent temperature stability are advantageous for many applications. While excellent lifetimes have been reported, lower early failure rates at high temperatures and high powers would be desirable, so we seek to better understand the aging process. Our past work has shown that dislocations grow not only in the active region (as expected) but also in the p-DBR. We have proposed that high-energy spontaneous emission from the active region is a driving force for degradation in the p-mirror layers. In the past year, we have been concentrating on developing new techniques to allow us to examine the VCSELs in plan view, and explore the radial extent of the degradation.