Executive Summary : | The development of atomically thin 2D layered materials like graphene, hexagonal boron nitride (hBN), transition metal dichalcogenides (TMDs), and their Van der Waals (vdW) heterostructures has led to the creation of advanced electronic and optoelectronic devices with superior properties. These materials exhibit a wide conductivity and bandgap range, from metallic to semiconducting and insulating. They can be further engineered by creating unconventional atomically sharp interfaces in the form of VdW heterostructures and superlattices, producing exotic physics and quantum phenomena such as interlayer and moire excitons, single-photon emission, and high-temperature Bose-Einstein condensates of excitons. However, there is limited knowledge about vertically aligned VdW heterostructures for electrically controlled light emitting applications. Recent reports on band structure engineered light-emitting diodes (LEDs) via multiple quantum well (MQW) vdW heterostructures have shown great promise for the fabrication of new functionality-enabled LEDs with vertical vdW heterostructures. To fully exploit the interlayer-quantum phenomena of vertical VdW heterostructure for high-performance new-concept optoelectronic devices, the primary challenge is the fabrication of atomically sharp and clean vertical heterointerfaces without polymer residues and atmospheric impurities. This research aims to explore and exploit the new concept-physics of quantum functionality-engineered in-situ developed VdW heterostructures of 2D TMDs, enabling quantum LEDs with spectrally sharp light emission. The proposed research includes developing the MOCVD growth-process for in-situ fabrication of vertically-aligned MoS2/MoSe2, WS2/WSe2, and MoS₂/WS₂ based VdW heterostructures, pursuing intentional Nb doping for high-quality p-type MoS₂ and WS₂ layers, and demonstrating quantum LED operation with developed p-type layers and VdW heterostructures sandwiched between hBN and graphene. |