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. The unintentional doping Si ion in the Indium phosphide (InP) wafer surface is responsible for the subsequent InGaAs epitaxial layer's mobility attenuation. Multi-type scattering processes determine the Si ion-induced mobility deterioration, and the dominant scattering mechanism is polar optical phonon scattering (Fröhlich scattering) in low ionized impurity concentration or high work 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.