Effects of crossed states on photoluminescence excitation spectroscopy of InAs quantum dots
1 Department of Applied Chemistry, National Chiao Tung University, 1001 Da Hsueh Rd., Hsinchu, 30010 Taiwan
2 Department of Electronics Engineering, National Chiao Tung University, 1001 Da Hsueh Rd., Hsinchu, 30010 Taiwan
3 Institute of Nanoscience, National Chung Hsing University, 250 Kuo Kuang Rd., Taichung 402, Taiwan
Nanoscale Research Letters 2011, 6:409 doi:10.1186/1556-276X-6-409Published: 2 June 2011
In this report, the influence of the intrinsic transitions between bound-to-delocalized states (crossed states or quasicontinuous density of electron-hole states) on photoluminescence excitation (PLE) spectra of InAs quantum dots (QDs) was investigated. The InAs QDs were different in size, shape, and number of bound states. Results from the PLE spectroscopy at low temperature and under a high magnetic field (up to 14 T) were compared. Our findings show that the profile of the PLE resonances associated with the bound transitions disintegrated and broadened. This was attributed to the coupling of the localized QD excited states to the crossed states and scattering of longitudinal acoustical (LA) phonons. The degree of spectral linewidth broadening was larger for the excited state in smaller QDs because of the higher crossed joint density of states and scattering rate.