RUI: Next Generation Rare Earth Based Light-Emitters for Solid-State Display & Quantum Information Technology Applications

The realization of a "smart society" will require advancements in display and quantum computation technologies. Examples of such technologies include microscale color-tunable pixels and the fabrication of systems whose quantum states can be precisely controlled, both of which can be addressed by "trapping" rare earth (RE) elements in a semiconducting host.

RE elements can be placed into various environments and retain most of their original atom-like properties, including emission wavelengths and spin states. Generally, RE ions are incorporated in passive, insulating materials. In this project, a team of researchers will study the properties of RE-doped semiconductors fabricated into structures such as diodes, microcavities, and microdisks.

The team will explore new ways to manipulate the RE ions by utilizing the strong interaction between the RE ions and other defects within the semiconductor hosts. Overall, this project will serve as the basis for a new generation of RE-doped semiconductor devices that harness quantum mechanical effects to achieve new functionalities such as the control of spins and the manipulation of light emission for quantum information processing and solid-state displays.

Through a collaboration between a predominantly undergraduate institution and two research universities in the greater Philadelphia area, this project will also train several undergraduate and graduate students from underrepresented groups for future employment in the quantum information and display industries.

Technical description.

Single electrically controlled color-tunable LEDs have been previously demonstrated in Eu-doped GaN, which is based on manipulating the state from which the Eu3+ ions emit. However, several details of the defect-specific energy-transfer pathways are still not fully understood. A deeper understanding of this process is crucial for optimizing such LEDs and for realizing controlled atomic emission in other RE-doped systems.

The team will also explore whether spin information can be transferred from injected carriers to the RE ions and vice-versa in novel optoelectronic devices. Measurements of optical transition linewidths, radiative lifetimes, and spin coherence times will establish the baseline potential of RE-doped semiconductors for quantum information protocols. With their high efficiency and narrow emission linewidth, Eu-doped GaN and Er-doped GaAs are promising candidates as single quantum emitters.

We aim to detect and address individual RE dopants by controlled dilute doping and enhancing the RE ions' radiative rates using photonic structures. Overall, the development of LEDs with full color-tunability will allow for the realization of single-contact RGB micro-LEDs, which will improve the performance of solid-state lighting technology and enable GaN-based active pixel displays.

For quantum computation applications, the combination of robust quantum states based on RE ions with the maturity of GaN and GaAs synthesis and nanofabrication technology can enable the rapid development of scalable quantum optoelectronic devices.

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.