Layer transfer of epitaxially grown Ge-lattice-matched Si27.8Ge64.2Sn8 films

The Ge-lattice-matched SiGeSn alloy offers a strong possibility of realizing superior crystalline and reliable SiGeSn-on-insulator (SiGeSnOI) structure for Ge-based optoelectronic devices. However, few reports exist on the Ge-lattice-matched SiGeSnOI structure and its applicability in such devices. Herein, we demonstrate the layer transfer of Ge-lattice-matched SiGeSn films using direct bonding and donor substrate removal to realize an SiGeSnOI structure. An Sn-rich Si27.8Ge64.2Sn8 alloy was epitaxially grown using a molecular beam epitaxy system at 200 degrees C. To remove the donor Ge substrate, we developed a two-step etching process using an H3PO4/ H2O2/H2O solution with high -speed Ge etching and an H2O2 solution with extremely high etch selectivity over SiGeSn. We observed nearly pure SiO2 formation as an etch-stop layer through SiGeSn wet oxidation. The SiGeSn metal-semiconductor-metal photodetector fabricated using the novel SiGeSnOI platform exhibited a photosensitivity of 9.03 mA/W at a wavelength of 1550 nm, which is promising for future group IV-based optoelectronic devices.