Role of Interfaces in Mechanical Response of Nano-heterostructures
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Established a method to quantify nucleation stresses for dislocations via in situ high-resolution transmission electron microscope experiment coupled with density functional theory calculation.
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Explained pure-shuffle nucleation of deformation twins in hexagonal-close-packed metals.
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Explained origin of multiple in-plane orientation of Cu in Cu/TiN nano-heterostructures.
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Explained role of chemistry at metal-nitride interfaces in dictating mechanical and structural properties metal/nitride nano-heterostructures.
Slip transfer from Nb to Mg nano-layer.
Materials growth mechanisms
Explaining growth of Zinc Blende AlN due kinetics driven N penetration in Al layer.
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Explained change in growth directions in ZnO nanowires under CO rich environment.
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Explained growth and stress-induced phase transformation of metastable zinc-blende AlN nanolayer grown by magnetron sputtering.
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Explained growth of MgCr2O4 spinel in Cr/MgO heterostructure under ion radiation.
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Explained thermodynamic driving force behind cations substitution in substoichiometric titania.
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Explained origin of chemically diffused interfaces across Ti/TiN nano-heterostructures, in collaboration with neutron reflectometry measurements.
Optoelectronic Properties of Materials
Range of bandgap observed in ZnSe/ZnTe nano-heterostructures strained to various levels.
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Suggested a practical way to engineer the bandgap of II-VI and III-V semiconductor through epitaxial strains in nano-heterostructures. This involved calculation of bandgap using density functional theory (DFT), hybrid DFT (HSE) and many body perturbation GW methods.
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Explained improved scintillation properties of LuxGd3-xAlxGa5-xO12 multicomponent garnets.
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Explained how band-edge engineering via doping can independently tailor either the conduction or valence band. These ideas extend to other complex oxides, and other applications requiring precise control of band gaps and edges, such as the rational design of optoelectronic devices.
Modeling of Line Defect from First-Princniples
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For the first time, using density functional theory (DFT), computed the lattice resistance to glide (Peierls stress) for the viable slip systems of multicomponent material (TiN).
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Using DFT calculation we show that six-layer bi-phase zinc blende AlN and wurtzite AlN can form a sharp interface. Three Shockley partials with the Burgers vectors pile up vertically and form the interface which separates the z-AlN from the w-AlN.
Charge density distribution at six-layer bi-phase zinc blende AlN and wurtzite AlN.