Chirped InGaAs quantum dot molecules for broadband applications
Department of Electrical Engineering, Faculty of Engineering, Semiconductor Device Research Laboratory (Nanotec Center of Excellence), Chulalongkorn University, Bangkok 10330, Thailand
Nanoscale Research Letters 2012, 7:207 doi:10.1186/1556-276X-7-207Published: 6 April 2012
Lateral InGaAs quantum dot molecules (QDMs) formed by partial-cap and regrowth technique exhibit two ground-state (GS) peaks controllable via the thicknesses of InAs seed quantum dots (x), GaAs cap (y), and InAs regrowth (z). By adjusting x/y/z in a stacked QDM bilayer, the GS peaks from the two layers can be offset to straddle, stagger, or join up with each other, resulting in multi-GS or broadband spectra. A non-optimized QDM bilayer with a 170-meV full-width at half-maximum is demonstrated. The temperature dependencies of the emission peak energies and intensities from the chirped QDM bilayers are well explained by Varshni's equation and thermal activation of carriers out of constituent quantum dots.