Towards Simultaneous Achievement Of Carrier Activation And Crystallinity In Ge And Gesn With Heated Phosphorus Ion Implantation: An Optical Study

We have investigated the optical properties of Ge and GeSn alloys implanted with phosphorus ions at 400 degrees C by spectroscopic ellipsometry from far-infrared to ultraviolet. The dielectric response of heated GeSn implants displays structural and transport properties similar to those of heated Ge implants. The far-infrared dielectric function of as-implanted Ge and GeSn shows the typical free carrier response which can be described by a single Drude oscillator. Bulk Ge-like critical points E-1, E-1 +/- Delta(1), E-0', and E-2 are observed in the visible-UV dielectric function of heated Ge and GeSn indicating single crystalline quality of the as-implanted layers. Although the implantation at 400 degrees C recovers crystallinity in both Ge and GeSn, an annealing step is necessary to enhance the carrier activation. (C) 2014 AIP Publishing LLC.