Reliability, Failure Modes, and Degradation Mechanisms in High Power Single- and Multi-Mode InGaAs-AlGaAs Strained Quantum Well Lasers

High power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well (QW) lasers are critical components for both telecommunications and potential space satellite communications systems. However, little has been reported on failure modes of state-of-the-art SM InGaAs-AlGaAs strained QW lasers although it is crucial to understand failure modes and underlying degradation mechanisms in developing these lasers that meet lifetime requirements for space satellite systems, where extremely high reliability of these lasers is required. Our present study addresses the aforementioned issues by performing long-term lifetests under different test conditions followed by failure mode analysis (FMA) and physics of failure investigation. We performed long-term accelerated life-tests on state-of-the-art SM and MM InGaAs-AlGaAs strained QW lasers under ACC (automatic current control) mode. Our life-tests have accumulated over 25,000 test hours for SM lasers and over 35,000 test hours for MM lasers. FMA was performed on failed SM lasers using electron beam induced current (EBIC). This technique allowed us to identify failure types by observing dark line defects. All the SM failures we studied showed catastrophic and sudden degradation and all of these failures were bulk failures. Our group previously reported that bulk failure or COBD (catastrophic optical bulk damage) is the dominant failure mode of MM InGaAs-AlGaAs strained QW lasers. To the best of our knowledge, this is the first report demonstrating that the dominant failure mode of both SM and MM InGaAs-AlGaAs strained QW lasers is the bulk failure. Since degradation mechanisms responsible for COBD are still not well understood, we also employed other techniques including focused ion beam (FIB) processing and high-resolution TEM to further study dark line defects and dislocations in post-aged SM and MM lasers. Our long-term lifetest results and FMA results are reported.