Insight into the origins of mobility deterioration in indium phosphide-based epitaxial layer

Ultra-high mobility speciality is a critical figure of merit for ultrapure materials and high-speed optoelectronic devices. However, unintentional doping-inducing various scattering frequently deteriorates mobility capacity. Therefore, how to elucidate the origin of mobility deterioration is still an open and technically challenging issue. Here we report that unintentional-doping silicon ion would be propagated into the indium phosphide (InP)’s epitaxial layer via analysis of time-of-flight and dynamic secondary ion mass spectrometry. The unintentional silicon ion in the InP wafer surface is responsible for the subsequent InGaAs epitaxial layer's mobility attenuation. The first-principles calculations and Boltzmann transport theory prove that polar optical phonon scattering (Fröhlich scattering) in non-doping InGaAs is the dominant scattering mechanism at high temperatures over 100 K. In contrast, the low-temperature scattering process is dominated by ionized impurities scattering. The unintentional silicon ion improves the Fröhlich scattering-dominated critical temperature. Our findings provide insight into the mobility degeneration originating from unintentional pollution and underlying scattering mechanisms, which lay a solid foundation for developing high-grade, super-speed, and low-power photoelectronic devices.