title: Ge microdisk with lithographically-tunable strain using CMOS-compatible process.
abstract: We present germanium microdisk optical resonators under a large biaxial tensile strain using a CMOS-compatible fabrication process. Biaxial tensile strain of ~0.7% is achieved by means of a stress concentration technique that allows the strain level to be customized by carefully selecting certain lithographic dimensions. The partial strain relaxation at the edges of a patterned germanium microdisk is compensated by depositing compressively stressed silicon nitride layer. Two-dimensional Raman spectroscopy measurements along with finite-element method simulations confirm a relatively homogeneous strain distribution within the final microdisk structure. Photoluminescence results show clear optical resonances due to whispering gallery modes which are in good agreement with finite-difference time-domain optical simulations. Our bandgap-customizable microdisks present a new route towards an efficient germanium light source for on-chip optical interconnects.
authors.forename: David S
authors.initials: DS
authors.lastname: Sukhdeo
authors.forename: Jan
authors.initials: J
authors.lastname: Petykiewicz
authors.forename: Shashank
authors.initials: S
authors.lastname: Gupta
authors.forename: Daeik
authors.initials: D
authors.lastname: Kim
authors.forename: Sungdae
authors.initials: S
authors.lastname: Woo
authors.forename: Youngmin
authors.initials: Y
authors.lastname: Kim
authors.forename: Jelena
authors.initials: J
authors.lastname: Vučković
authors.forename: Krishna C
authors.initials: KC
authors.lastname: Saraswat
authors.forename: Donguk
authors.initials: D
authors.lastname: Nam