Semiconductor light emitters, particularly lasers and light emitting diodes (LEDs), have served as the driving force for many of the most significant advances in technology over the past five decades. From the telecom lasers used in our communications networks, to the LEDs reducing energy consumption in solid state lighting applications, semiconductors offer compact, low cost, and efficient light sources for a broad range of technological advances. However, the majority of the aforementioned sources and applications lie in the visible and near-infrared portions of the electromagnetic spectrum. With a few exceptions, the longer wavelength mid-infrared (mid-IR) lacks semiconductor-based light sources of equivalent utility and efficiency, despite being a wavelength range of significant technological importance for a range of biomedical, environmental, industrial, as well as security and defense, applications. The lack of semiconductor sources in this wavelength range can largely be attributed to the intrinsic inefficiency of mid-IR optoelectronic materials, which dissipate energy more efficiently as heat than as light. The inherent inefficiency of mid-IR emitters, however, offers very real opportunities for implementing new approaches for efficiency enhancement unique to these long wavelengths. This project seeks to transform the field of mid-IR semiconductor light emitters by marrying recent advances in epitaxial materials growth, light-matter interactions, and semiconductor device architectures to develop a class of efficient semiconductor mid-IR light sources, with potential applications in infrared quantum communications, infrared sensing, thermal signaling, and biomedical imaging. Our technical efforts will be augmented by a robust K-12 outreach program, as well as sustained REU and RET mentoring.
The field of plasmonics has promised a broad range of transformational advances in optics and optoelectronics, including but not limited to, on-chip sub-diffraction limited waveguiding, higher efficiency photovoltaics, sub-diffraction limit and ultra-efficient emitters, and enhanced sensitivity sensor systems. Research efforts on the above have largely focused on the near-infrared and visible wavelengths of the electromagnetic spectrum (400 nm - 3um), where efficient emitters abound, and the introduction of plasmonic materials generally results in decreased emission efficiency (even if other benefits, such as sub-wavelength confinement, are demonstrated). The mid-IR (3 - 30 um), on the other hand, is a wavelength range largely devoid of efficient emitters, where plasmonics can be leveraged to improve, not degrade, emitter efficiency. The mid-IR is also a wavelength range where high quality plasmonic materials and quantum engineered and nanostructured emitters can be grown epitaxially in the same material system. This project will utilize the highly-doped semiconductor 'metals' platform, combined with quantum engineered active regions and patterned epitaxial growth, to develop new, increased efficiency, mid-IR sources in a monolithic semiconductor platform. The project will offer transformational opportunities for fundamental investigation of light-matter interactions between quantum engineered emitters and designer plasmonic structures. At the same time, the project will look to demonstrate that plasmonics can be leveraged to realize significant improvements in mid-IR source efficiency. The ultimate goal of the project is the demonstration of the first electrically-driven all-semiconductor plasmonic/quantum-emitter sources for efficient mid-IR light emitting devices and their subsequent integration into mid-IR optical systems. The PIs have strong track records of outreach to the larger Austin community, and as part of the proposed effort will strengthen these ties with regular outreach and modular activities in K-12 classrooms. The PIs have a commitment to diversity in their research groups, and will build off of this diversity and look to recruit a talented and diverse group of students to the project, which will expose participating students to cutting edge research in crystal growth, optics, device design and materials and device characterization. The PIs will advise undergraduate students and local K12 teachers through existing summer REU and RET programs at UT.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
