Electrical Injection Nanolasers Based on 2D Monolayer Gain Material

Arizona State University, Scottsdale AZ

Investigators

Abstract

Nanoscale lasers are important for a wide range of applications, especially in optical interconnects for integrated nanophotonic circuits in future computers. Despite great progress made, no such light source currently meets the stringent requirements of future on-chip interconnects. Current semiconductor lasers consume ~ 0.1-1 pico (one trillionth) joule of energy per bit of information transmitted; however, the required lasers must consume less than 0.01 pico-joule of energy per bit, which in turn limits the dimensions of such lasers to 100s of nanometers to displace electronic interconnects. The proposed project focuses on fundamental research to develop such nanoscale light sources with high energy efficiency. If successful, the research would have far reaching societal, economical, and educational impacts by 1) addressing energy efficiency issue, because the amount of internet-related energy consumption is increasing at a rate that far exceeds the current increasing capacity of energy generation; 2) training undergraduate and graduate students, especially those from the underrepresented groups, in research and development of green-photonic technology through nanophotonic device design, nano-fabrication, and the development of future computer technologies. Nanoscale lasers require two key ingredients: a small cavity to confine photons and efficient optical gain materials. One of the most efficient and smallest-volume gain media emerged recently is the two-dimensional (2D) layered materials of transition metal di-chalcogenides (TMDCs). Recent research has demonstrated lasing using only a single layer of TMDCs. These studies have demonstrated 2D materials as potentially the most efficient gain materials. But all experiments to date have required optical pumping, while their operation under electrical injection is necessary for on-chip applications. The proposed efforts aim at developing the first electrical-injection nanolasers based on 2D TMDCs to address the fundamental challenges of energy efficiency. The proposed approach combines the most efficient optical gain material of 2D TMDCs with high-quality silicon cavities to fabricate the most energy-efficient nanolasers. The 2D materials operating on excitonic transitions provide several benefits to nanolasers: the most efficient optical gain material, the smallest gain volume to achieve lasing, and ease of integration into a silicon platform. The Si-nanobeam cavity provides the highest quality factor with the lowest possible laser threshold, while offering advantages of compatibility with electronics and maturity in fabrication. Such an electrical injection nanolaser on a Si-platform is ideally suited for optical interconnects and other Si-based applications. The objective of the proposal is to study the carrier injection into 2D monolayer molybdenum ditelluride with optimized design to achieve the first electrical injection nanolaser using a 2D gain material on a Si-platform by combining theoretical design and simulation with experimental fabrication and characterization. Achieving this objective would lay the ground work for development of a variety of future devices for use in sensing and chip-level interconnects for future energy-efficient computers. 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.