Wafer bow control of extended wavelength InGaAs photodetector materials by strain tailoring

The wafer bow caused by lattice mismatch between metamorphic InGaAs epitaxial layer and InP substrate has become one of the key factors limiting the large-scale development of extended wavelength InGaAs focal plane array photodetectors. By introducing tensile strain in InAlAs buffer layers and InAlAs cap layer to compensate the compressive strain caused by lattice mismatch, the wafer bow was decreased from 55.9 μm to 22.2 μm. The influence of strain compensation structure on the anisotropy of metamorphic InGaAs materials was investigated by stress distribution, surface morphology, and PL uniformity. XRD and PL characterizations indicate that small tensile strain in InAlAs buffer layers did not reduce the quality of metamorphic InGaAs epitaxial material. This study shows that strain compensation is an effective method to control wafer bow and decrease anisotropy of metamorphic InGaAs materials grown on InP substrate.