A new class of atomically thin materials, so called two dimensional semiconductors, has gained considerable interest as a viable material for optoelectronic devices such as lasers and light emitting diodes. Previous research reports that these new materials suffer from detrimental environmental interactions and material defects that result in low light emission efficiencies, thereby impeding practical applications. This project ultimately enables an efficiency and performance boost for nanoscale light sources such as nanolasers as well as novel quantum light sources that are required in upcoming technologies that use light instead of electrons to realize densely integrated information processing directly on a semiconductor chip. The research approach utilizes a promising crystal growth technique that leads to very low defect densities in two dimensional materials. The research also integrates these materials with optical devices that can focus the light into extremely small spots, leading to drastically enhanced light emission efficiency from these semiconductors. The educational activities include reaching out to underrepresented groups as well as training the next generation of scientists and engineers in materials growth, clean-room fabrication and optical characterization, and through introducing new research-based educational materials into the graduate curriculum.
Monolayer transition metal dichalcogenides are semiconductor materials that have gained considerable interest for optoelectronic and valleytronic applications but are often found to suffer from environment interactions and material defects that lead to low quantum efficiencies. This project integrates two-dimensional heterostructures featuring ultralow-disorder environments with low-group-velocity plasmonic band-edge modes in order to investigate lasing and quantum coherence signatures of on-chip nanolasers with highly-directional output. This project furthermore explores gate-tunable exciton and trion gain and realizes deterministic positioned quantum emitters coupled to plasmonic gap modes deeply in the Purcell regime. The research approach combines material growth, 2D assembly, and nanofabrication to enable transformative advances for the field of on-chip photonics and quantum information science that aims to facilitate the outstanding optical properties of "intrinsically-clean" 2D semiconductors. The integration with plasmonic nanocavities offers exciting new inroads to directly tailor the light-matter interaction in the Purcell and strong-coupling regime. Ultimately, this project enables an efficiency and performance boost for on-chip nanolasers for the integration in optical circuits, as well as for single-photon sources required for quantum information science; these are all affected by the exciton photophysics and significantly benefit by low-disorder environments, reduced material defects in flux-grown material, and plasmonic coupling to directly increase the quantum yield. The project also puts forth an outreach model that focusses on building long-term relationships with the Columbia Secondary School for Math, Science, and Engineering, a public, 6-12 school with a predominant Hispanic and African-American student population. Outreach activities to under-represented groups will leverage Stevens' institutional affiliations with organizations such as the Women in Engineering Program and the National Action Council for Minorities in Engineering (NACME).
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.
