We report high-power multi-junction vertical-cavity surface-emitting
lasers (VCSELs) with a significantly suppressed carrier leakage issue
under high injection current and temperature. By carefully optimizing
the energy band structure of quaternary AlGaAsSb, we obtained a
12-nm-thick AlGaAsSb electron-blocking layer (EBL) with a high
effective barrier height (∼122 meV), a low compressive strain
(∼0.99%), and a reduced electronic leakage current. The resulting
three-junction (3J) 905 nm VCSEL with the proposed EBL exhibits an
improved maximum output power (∼46.4 mW) and power conversion
efficiency (PCE; ∼55.4%) during room-temperature operation. Also, it
was found from thermal simulation that the optimized device shows more
advantages over the original device during high-temperature operation.
The type-II AlGaAsSb EBL provided an excellent electron-blocking
effect and would be a promising strategy for multi-junction VCSELs to
realize high-power applications.
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