AlAsP-based strain-balancing in MOVPE-grown distributed Bragg reflectors

• AlAsP/GaAs strain balanced distributed Bragg reflectors.
• Individual thicknesses are determined by in-situ reflectance fitting.
• P mole fraction determination based on in-situ curvature fitting.
• Accumulated tensile strain during growth limited by means of an upper limit of the strain-thickness product.
• Mixed quarter-wave/triple quarter-wave approach for an AlAs(y)P(1−y)/GaAs period reduces RT curvature from −142 km−1 to −76 km−1.

We demonstrate a way to reduce the room temperature wafer bow of AlAs/GaAs super-lattices (SL) by the addition of phosphorus forming an AlAsyP1−y/GaAs SL. In-situ monitoring of the curvature not only allows for a determination of the AlAsyP1−y composition, but also to assess the onset of relaxation by means of the strain-thickness product in conjunction with curvature transient simulation. Based on this, we were able to realize an approach where the effective strain within one SL period is lowered by increasing the GaAs thickness while maintaining a high reflectivity at design wavelength. This lowers the cool down curvature swing and thus yields a RT curvature reduction from −142 km−1 to −76 km−1.