Terahertz Absorption of (In,Ga)As Quantum Post Nanostructures*

Quantum posts (QPs) are a new kind of self-assembled semiconductor nanostructure created by vertical stacking of self-assembled InAs quantum dots into roughly cylindrical In rich regions embedded in a GaAs matrix.$^{2}$ These structures have potential applications for THz quantum information processing,$^{1}$ THz generation, and THz detection. For a single electron trapped in a 40 nm high QP, the orbital transition between the ground and first excited state is predicted to occur near 1 THz.$^{2}$ Voltage controlled electron loading of QPs is measured by capacitance-voltage spectroscopy. Terahertz absorption spectroscopy of electrons in quantum post samples is demonstrated as a function of electron loading. $^{1}$ M. S. Sherwin, A. Imamoglu and C. Montroy, PRA 60, 3508 (1999) $^{2}$ J. He et al, Nanoletters 7, 802 (2007)