Synthesis of Ge_(1-x)Sn_(x) Alloy Thin Films Using Ion Implantation and Pulsed Laser Melting (II-PLM)

摘要

Ge_(1-x)Sn_(x) thin films are interesting for all-group-IV optoelectronics because of a crossover to a direct bandgap with dilute Sn alloying. However, Sn has vanishing room-temperature equilibrium solubility in Ge, making their synthesis very challenging. Herein, we report on our attempts to synthesize Ge_(1-x)Sn_(x) films on Ge (001) using ion implantation and pulsed laser melting (II-PLM). A maximum of 2 at.percent Sn was incorporated with our experimental conditions in the samples as determined by Rutherford back scattering spectroscopy. A red-shift in the Ge optical phonon branch and increased absorption below the Ge bandgap with increasing Sn concentration indicate Sn-induced lattice- and band-structure changes after II-PLM. However, ion-channeling and electron microscopy show that the films are not of sufficient epitaxial quality for use in devices.