InAs Band-Edge Exciton Fine Structure
Abstract
Semiconductor nanocrystals rarely, if ever, exhibit emission linewidths which are lifetime-limited. Instead, there are a number of linewidth broadening mechanisms which are relevant under various conditions, such as spectral diffusion, charging, and excitonic fine structure. While spectral diffusion and charging are most likely photoinduced effects and thus can be modulated by the excitation rate of the nanocrystals, fine-structure broadening is fundamental to the photophysics of nanocrystals and most likely unavoidable. A complete understanding of the excitonic energy landscape enables us to determine dephasing rates, linewidths, lifetimes, and other parameters essential to optical applications. Here we discuss the relationship between the excitonicfine structure and the emission dynamics of InAs/CdS core/shell nanocrystals. At room temperature wefind steady-state emission dynamics on order of 150 ns, and as the temperature is lowered wefind that the relaxation is greatly slowed (1:9 s at 3:6K). Wefind that these emission dynamics are well-explained by a band-edge model including a pair of "dark" and "bright" excitonic states, separated in energy by 2:3 meV.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 29, 2015
- Accession Number
- AD1034763
Entities
People
- Daniel Franke
- Daniel Harris
- Eric Dauler
- Greg Steinbrecher
- Igor Coropceanu
- Matt Grein
- Oscar Sandoval
- Ryan Wilson
- Thomas Bischof
Organizations
- MIT Lincoln Laboratory