Strain-induced effects on the performance of AlGaInP visible lasers

The strain-induced reduction of the threshold current density (J_th) of AlGaInP visible lasers was investigated. Strained multiple-quantum-well (SMQW) and unstrained MQW AlGaInP broad contact lasers were fabricated using low-pressure organometallic vapor phase epitaxy (OMVPE). To evaluate the strain-induced effects, AlGaInP compressively strained quantum wells were introduced into the active region of the SMQW laser, making the energy band structure of the SMQW laser almost the same as that of the MQW one. Comparing the J _th of both lasers at the same lasing wavelength showed that, for cavity lengths between 300 and 700 μm, more than a 4% decrease in J_th was obtained by incorporating the SMQW structures, and the maximum reduction of 6% was achieved at 500 μm. In addition, it was shown that, in the SMQW laser, the considerable decrease in the transparency current density J₀ contributes effectively toward J_th reduction