The effects of selenium doping on performances of MOVPE grown compressively strained (Al)GaInP lasers

Visible light source (Al)GaInP laser is finding applications in many fields such as optical data storage, barcode scanning, low-cost data transmission via plastic optical fiber, laser printers and optical pumping of tunable Cr³⁺-doped solid state lasers (hosts are alexandrite or LiSAF), but, to be well used in such fields, low threshold current densities of visible (Al)GaInP laser diodes are critically required due to the poor thermal-transport characteristic of AlGaInP. Because of the smaller conduction band offset of AlGaInP material system compared to that of AlGaAs, the electron leakage through heterobarrier in p-side was well known to take a big part of the total current leakage. Both higher doping level in p-side and multi-quantum-barrier (MQB) structure are suggested to suppress the electron leakage. In addition, laser structures with graded index (GRIN) barrier layers proved to be effective to confine carriers in active layers. In this letter, we report the effects of selenium doping in n-type cladding layers on the performances of compressively strained (Al)GaInP lasers