title: Core-Shell Germanium/Germanium-Tin Nanowires Exhibiting Room-Temperature Direct- and Indirect-Gap Photoluminescence.
abstract: Germanium-tin alloy nanowires hold promise as silicon-compatible optoelectronic elements with the potential to achieve a direct band gap transition required for efficient light emission. In contrast to Ge1-xSnxepitaxial thin films, free-standing nanowires deposited on misfitting germanium or silicon substrates can avoid compressive, elastic strains that inhibit formation of a direct gap. We demonstrate strong room temperature photoluminescence, consistent with band edge emission from both Ge core nanowires, elastically strained in tension, and the almost unstrained Ge1-xSnxshells grown around them. Low-temperature chemical vapor deposition of these core-shell structures was achieved using standard precursors, resulting in Sn incorporation that significantly exceeds the bulk solubility limit in germanium.
authors: Department of Materials Science and Engineering, ‡Stanford Nanofabrication Facility, §Stanford Nano Shared Facilities, and ∥Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Andrew C
authors: AC
authors: Meng
authors: Department of Materials Science and Engineering, ‡Stanford Nanofabrication Facility, §Stanford Nano Shared Facilities, and ∥Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Colleen S
authors: CS
authors: Fenrich
authors: Department of Materials Science and Engineering, ‡Stanford Nanofabrication Facility, §Stanford Nano Shared Facilities, and ∥Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Michael R
authors: MR
authors: Braun
authors: Department of Materials Science and Engineering, ‡Stanford Nanofabrication Facility, §Stanford Nano Shared Facilities, and ∥Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors: James P
authors: JP
authors: McVittie
authors: Department of Materials Science and Engineering, ‡Stanford Nanofabrication Facility, §Stanford Nano Shared Facilities, and ∥Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Ann F
authors: AF
authors: Marshall
authors: Department of Materials Science and Engineering, ‡Stanford Nanofabrication Facility, §Stanford Nano Shared Facilities, and ∥Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors: James S
authors: JS
authors: Harris
authors: Department of Materials Science and Engineering, ‡Stanford Nanofabrication Facility, §Stanford Nano Shared Facilities, and ∥Department of Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Paul C
authors: PC
authors: McIntyre
keywords: Germanium−tin; core−shell nanowire; optoelectronics; photoluminescence