Ge_0.75Sn_0.25 on insulator metal-semiconductor-metal photodetector by layer transfer technique

Abstract The Ge 0.75 Sn 0.25 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. A Ge 0.75 Sn 0.25 OI metal-semiconductor-metal (MSM) photodetector was 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, SiO 2 and DVS-BCB. The photoresponse of the Ge 0.75 Sn 0.25 OI 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 × 10 −6 A W −1 and ∼1 × 10 −6 W/Hz 0.5 , respectively. The thermal budget for fabricating Ge 0.75 Sn 0.25 OI 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.