Luminescent germanium and group IV quantum dots : synthesis and surface passivation

Abstract

The narrow bulk band gap and large exciton Bohr radius of germanium (Ge) make it an attractive material for optoelectronics utilizing band gap tunable photoluminescence (PL). However, realization of PL due to quantum confinement remains scarcely reported. Instead, PL is often observed from surface defect states. In this research, tunable band gap PL is demonstrated by chemically passivating the Ge nanocrystal (NC) surface. The exchange of native Ge-Cl surface groups with alkyl groups using grignard reagents leads to the first instance of tunable band gap emission from free-standing Ge NC's, synthesized by a non thermal Argon plasma. Ge NC's between 4.8 nm and 10.2 nm diameter exhibit near infrared emission featuring spectral line widths that are at least a factor of two narrower than any previous report.

Date of Award	31 Aug 2013
Original language	English
Supervisor	Gerrit M.W. Kroesen (Supervisor 1) & U.R. Kortshagen (Supervisor 2)