ABSTRACT
Self-assembly of quantum dots has yielded early laser devices in which a single layer or multiple layers of uniform quantum dots serve as the gain medium [1,2]. Selfassembly is advantageous from a production standpoint because of the relatively simple fabrication process. The advantages of self-assembly can be applied to more complex and integrated devices by modifying the quantum dot growth process to localize the area of self-assembly in controlled ways. This has previously been accomplished by a variety of methods including preferential growth on particular substrate facets [3], prepatteming of the substrate with a silicon nitride [4, 5] or silicon dioxide [6, 7] growth mask, and in situ electron beam lithography and etching to increase crystal step edge density in localized regions [8]. We have previously reported a technique for areacontrolled quantum dot self-assembly using prepattemed InGaAs thin films which modify the local indium deposition required for self-assembly [9-11]. This technique is advantageous because it does not result in quantum dot size fluctuations across the growth region due to diffusion of growth precursors as does the use of a dielectric growth mask. Additionally, it allows for variation of the quantum dot size, and therefore transition energy, between different, simultaneously grown dot regions through modification of the InGaAs thin film thickness.
