Pathways for quantum dot optoelectronics fabrication using soft nanoimprint lithography

Abstract

Nanoimprint lithography is a low-cost, high-throughput alternative to traditional serial nanolithography technologies. Here it is explored for application in the optoelectronics area. A variant of NIL using a flexible polymeric mold, termed “soft NIL” is used to create and study quantum dot arrays according to two concepts. In the first concept, a dense array of nano-sized holes are etched into a blank GaAs substrate. When a thin InAs quantum dot (QD) layer is grown on top, the QDs nucleate only at the locations of the holes, resulting in an array of site-controlled quantum dots. This concept shall be called “regrown QDs.” In the second concept, soft NIL is used to pattern an etch mask atop a sample consisting of an InP substrate topped by an InGaAs quantum well. Anisotropic dry etching is used to etch the sample down to the InP substrate to form an array of pillars, each containing a QD. For each concept, the morphology and optical performance are studied, and refinements are pursued to gain finer control over the morphology and brighter luminescence from the QDs. Finally, a plan is presented for incorporation of each concept into a double heterostructure layer design to yield a quantum dot laser.