Self-aligned process for forming microlenses at the tips of vertical silicon nanowires by atomic layer deposition

摘要

The microlens is a key enabling technology in optoelectronics, permittinglight to be efficiently coupled to and from devices such as image sensors andlight-emitting diodes. Their ubiquitous nature motivates the development of newfabrication techniques, since existing methods face challenges as microlensesare scaled to smaller dimensions. Here, we demonstrate the formation ofmicrolenses at the tips of vertically-oriented silicon nanowires via a rapidatomic layer deposition (ALD) process. The nature of the process is such thatthe microlenses are centered on the nanowires, and there is a self-limitingeffect on the final sizes of the microlenses arising from the nanowire spacing.Finite difference time domain electromagnetic simulations are performed ofmicrolens focusing properties, including showing their ability to enhancevisible-wavelength absorption in silicon nanostructures.