Work was conducted via 6 work packages (WPs). In WP1, the Fellow further developed the light-matter interaction model available in the OMEN quantum transport solver. This state-of-the-art device simulator is maintained in the Nano-TCAD research group of Prof. Mathieu Luisier at ETH Zurich. Relying on the density-functional theory (DFT) and the NEGF formalism, predictive simulations of the I-V characteristics of vdWHs as well as of their photo-response properties were efficiently calculated on high-performance supercomputers. Light-matter interactions were taken into account from first-principles to enable accurate performance predictions. This fully ab initio simulation framework relies solely on the knowledge of the atomistic structures of the materials and the device configuration. The complex band structure, band edge alignment of vdWHs, electrostatics in 3-D and required quantum mechanical effects such as tunnelling and confinement are automatically captured. WP1 yielded 1 conference publications and 3 journal publication to date, with 1 journal manuscripts underway.
In WP2, the Fellow specifically investigated 2-D transition-metal dichalcogenides (TMDCs) and their vdWHs. From DFT calculations, the MoSe2-WSe2 combination was identified to show strong light-matter interaction. The Fellow investigated light-matter interactions and charge transport in MoSe2-WSe2 vdWH PIN photodiodes under the influence of a monochromatic electromagnetic light. In addition, he examined a carefully engineered defective 2-D crystal, PtSe2, and discovered that Se vacancies in bilayers break the centrosymmetry of the crystal. The defective bilayers exhibit 10 times larger photo-response than the pristine ones. This peculiar effect is known as bulk photo-voltaic effect (BPVE) and has only been observed in some special non-centrosymmetric materials. The BPVE can lead to photogeneration of hot and non-equilibrium electrons and above-gap photovoltage. The simulated photo-response of the defective bilayer PtSe2 agrees very well with the experiment data of the collaborator. In WP2, the Fellow delivered 1 conference publications and 1 journal publication to date, with 1 journal manuscript underway.
WP3 involved developing a self-consistent GW (scGW) method in our quantum transport simulator to include electron-electron interactions in non-equilibrium systems, from first-principles. This scGW method goes beyond the state-of-the-art and allows for many-body simulations of hot-carrier effects in advanced solar cells. By identifying novel 2-D materials and designing vdWH to enhance the CM effect, the power conversion efficiency can be theoretically increased above the Shockley-Queisser limit. The Fellow contributed in the prestigious IEEE International Electron Devices Meeting, with additional 1 conference publication and 3 journal manuscripts underway. In WP5, for researcher training, the Fellow attended 6 intensive training workshops and multi-day conferences. In WP6, for transfer of knowledge, he provided supervision and mentoring for semester projects and Master thesis. He was appointed Guest Editor of Frontiers In Electronics. The project was managed under WP4.
