Intellectual Merit. Improved thermal engineering is critical to improving the operating characteristics and lifetimes of optoelectronic devices that are central to photonics applications such as wavelength division multiplexed and high-speed communications networks. However, conventional macroscopic theory often cannot accurately predict thermal behavior in devices engineered on the micro- or nano-scale. Likewise, experimental exploration of the remarkably complex heat generation and transport processes in nano-structured optoelectronic devices is also challenging, in large part because the primary heat sources are often buried deep within these devices. The work proposed here will provide a dramatic contribution to thermal engineering of optoelectronic devices by enabling for the first time high-resolution experimental measurements of temperatures deep within an operating device. We will develop a confocal thermoreflectance technique to measure 3-D temperature profiles with spatial resolutions on the order of 150nm (lateral) and 550nm (vertical), along with 10-25mK thermal resolution. This is an order of magnitude better spatial resolution and a two order of magnitude improvement in thermal resolution relative to commercial IR microscopes. High resolution experimental measurements of the thermal distribution both within operating devices and also at the boundaries will be combined with detailed theoretical modeling of heat generation and transport within complex heterostructured devices. The proposed state of the art, confocal thermoreflectance technique will enable us to achieve the following three technological advances: a) non-invasive, 3-D thermal profiling inside operating optoelectronic devices; b) analyze heat transport in complex optoelectronic devices; and c) determine mechanisms for internal heat generation in homojunctions and heterostructured devices.
Broader impact: This proposal will significantly enhance the infrastructure for research and education at Mt Holyoke College, by creating a novel facility for high-resolution, nanoscale thermal imaging. This facility will lead to new partnerships with both international and industrial collaborations, as well as strengthening our participation in the existing local 5-College network with the University of Massachusetts at Amherst. Furthermore, the proposal integrates research with education: 6-8 undergraduate women will work on this project, in collaboration with the PI and a 5-College postdoctoral researcher. Mt. Holyoke places a particular premium on the integration of cutting-edge research into the education of the next generation of women scientists and engineers, so undergraduates will be heavily involved in all aspects of the proposed research. Finally, because Mt Holyoke is a women's college with an unusually diverse student body and the PI is heavily involved in a number of activities to diversify access to the sciences, the proposed research comprises a remarkable opportunity to broaden the participation of underrepresented students in science.
