Ge0.75Sn0.25 on insulator metal-semiconductor-metal photodetector by layer transfer technique

Abstract The Ge0.75Sn0.25 alloy, which is lattice matched to the InP, has the potential to create a high-quality GeSn-on-insulator (GeSnOI) structure for group IV optoelectronic devices. Ge0.75Sn0.25OI metal-semiconductor-metal (MSM) photodetector were fabricated through the layer transfer technique using DiVinyl Siloxane bis-Benzocyclobuten (DVS-BCB) polymer as an adhesive and highly selective wet etching of InP substrate over GeSn, Si, SiO2 and DVS-BCB. The photoresponse of Ge0.75Sn0.25OI MSM photodetector at a wavelength of 1550 nm was evaluated using a modulated laser and lock-in method, achieving a responsivity and a noise equivalent power (NEP) of ~3 x 10−6 A/W and ~1 x 10−6 W/Hz0.5, respectively. The thermal budget for fabricating Ge0.75Sn0.25OI MSM photodetector is below 220 °C, which is compatible with conventional Si back-end-of-the-line (BEOL) processing toward three-dimensional (3D) heterogeneous-integrated devices.