Title: 3D Photonic Crystals for Controlling the Emission and Flow of Light: Implications for Solar Energy and Light Emitting Diodes
Optoelectronic devices have long benefited from structuring in multiple dimensions on microscopic length scales. However, preserving crystal epitaxy, a general necessity for good optoelectronic properties, while imparting a complex three-dimensional structure remains a significant challenge. Three-dimensional (3D) photonic crystals are one class of materials where epitaxy of 3D structures would enable new functionalities. Many 3D photonic crystal devices have been proposed, including zero-threshold lasers low-loss waveguides high-efficiency light-emitting diodes (LEDs) and solar cells, but have generally not been realized because of material limitations. Exciting concepts in metamaterials, including negative refraction and cloaking, could be made practical using 3D structures that incorporate electrically pumped gain elements to balance the inherent optical loss of such devices. Here I will discuss the 3D-template-directed epitaxy of group III-V materials, which enables formation of 3D structured optoelectronic devices and illustrate the power of this technique by fabricating an electrically driven 3D photonic crystal LED. Time permitting, I will also discuss 3D thermophotovoltatic devices and the required materials, as well as the embedding of emissive defects within 3D photonic crystals.