GaAs-based laser diodes emitting in the red spectral region have challenging material and thermal properties when reducing the emission wavelength towards the physical limit around 630 nm. To improve the properties of such laser diodes, we have optimized the growth parameters of the GaInP quantum wells (QW) embedded in AlGaInP. The growth temperature and the V/III ratio during growth of the QW was varied. By reducing the QW growth temperature from 770 to 700 degrees C, an improvement of the laser performance was achieved at 635 and at 643 nm laser emission wavelength. By increasing the V/III ratio, a higher photoluminescence intensity could be achieved in QW test samples. Combining both approaches important laser parameters like threshold current density, differential efficiency and internal absorption were improved substantially. (c) 2008 Elsevier B.V. All rights reserved.