D8.

Project title: Effect of surface modification on the excited-state properties of silicon quantum dots and silicon nanowires, a multi-level theoretical study

 

Silicon (Si) nanostructures are one most attractive nanomaterial for optoelectronics, due to the well-established Si technology. Besides control growth of Si nanowires (SiNWs), we are also actively engaging in exploring their various applications, in particular those relating to their optical properties. However, a number of mechanistic issues, particularly luminescence mechanisms and effects of surface species on optical properties, still need further understanding. To guide and complement experimental efforts, a systematic theoretical research is essential and timing.

 

This project aims to systematically study the excited-state properties and resolve the signatures in optical absorption and emission of Si quantum dots and SiNWs with and without surface modifications. The study will be conducted using multi-level theories including conventional time-dependent density-functional theories and a new approach based on optimized effective potential. Species/molecules containing H, C, N, O, and F of chemical and/or biological importance will be considered for the surface modification. Particular attention will be paid to the excited-state relaxation and other physical processes including indirect-to-direct band gap transition, and tuning of emission and fluorescence yield due to surface modifications. The results will provide the needed understanding of the luminescence mechanisms from Si nanostructures, which will facilitate their applications in optoelectronics and chemical/biological sensings.



Supervisor:
Prof R Q Zhang (aprqz@cityu.edu.hk)

Suitable for
: M.Phil./Ph. D