title: Observation of improved minority carrier lifetimes in high-quality Ge-on-insulator using time-resolved photoluminescence.
abstract: We report improved minority carrier lifetimes in n-type-doped and tensile-strained germanium by measuring direct bandgap photoluminescence from germanium-on-insulator substrates with various levels of defect density. We first describe a method to fabricate a high-quality germanium-on-insulator substrate by employing direct wafer bonding and chemical-mechanical polishing. Raman spectroscopy measurement was performed to assess the purity of the transferred layer on an insulator. Using time-resolved photoluminescence decay measurement, we observe that minority carrier lifetimes can be improved by over a factor of 3 as the defective top interface of our material stack is removed. Our high-quality germanium-on-insulator should be an ideal platform for high-performance, germanium-based photonic devices for on-chip optical interconnects.
authors.forename: Donguk
authors.initials: D
authors.lastname: Nam
authors.forename: Ju-Hyung
authors.initials: JH
authors.lastname: Kang
authors.forename: Mark L
authors.initials: ML
authors.lastname: Brongersma
authors.forename: Krishna C
authors.initials: KC
authors.lastname: Saraswat