Abstract

We investigate a new class of quantum-well (QW) and quantum-dot (QD) coupled laser structure,^1,2 which is distinct from the most commonly used dots-in-a-well structure.^3,4 This quantum-dot laser employs auxiliary quantum wells coupled to the quantum dots via tunneling through thin barriers for electron and hole injection, Fig. 1. The injected carriers are first collected by the quantum wells, followed by tunneling into the quantum dots, with subsequent relaxation to the ground states for laser action. The quantum wells overcome the limits of carrier collection, lateral transport, and thermalization of the quantum dots. Room temperature continuous operation of this laser structure with photopumping¹ and electrical injection² has been demonstrated experimentally. The laser performance of these new quantum-well to quantum-dot tunneling structure is also shown to perform better than the earlier version of quantum-dot layer achieved by optical pumping.⁵ Tunneling injection of carriers into the quantum dots has been studied theoretically for ultrahigh temperature stability.⁶ However, the tunneling rate from the quantum-well into the quantum-dot remains to be investigated.

© 2002 Optical Society of America