Non-inverted electron-hole alignment in InAs/InP self-assembled quantum dots

Photoluminescence from individual InAs/InP quantum dots embedded within a planar n–i structure is studied as a function of vertical electric field. We demonstrate control of the electron number and determine the Stark shift and built-in dipole at zero electric field. In contrast to the well studied InAs/GaAs quantum dot material system, we obtain a built-in dipole which indicates that the electron lies above the hole at zero electric field. The magnitude and direction of the measured dipole suggests a uniform quantum dot composition. The gating principles we demonstrate can be applied to pre-positioned InAs/InP quantum dots, such that arrays of initialized single spins can be employed for quantum information applications. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)