Interlaced, Nanostructured Interface with Graphene Buffer Layer Reduces Thermal Boundary Resistance in Nano/Microelectronic Systems

Improving heat transfer in hybrid nano/microelectronic systems is a challenge, mainly due to the high thermal boundary resistance (TBR) across the interface. Herein, we focus on gallium nitride (GaN)/diamond interfaceas a model system with various high power, high temperature, and optoelectronic applicationsand perform extensive reverse nonequilibrium molecular dynamics simulations, decoding the interplay between the pillar length, size, shape, hierarchy, density, arrangement, system size, and the interfacial heat transfer mechanisms to substantially reduce TBR in GaN-on-diamond devices. We found that changing the conventional planar interface to nanoengineered, interlaced architecture with optimal geometry results in >80% reduction in TBR. Moreover, introduction of conformal graphene buffer layer further reduces the TBR by ∼33%. Our findings demonstrate that the enhanced generation of intermediate frequency phonons activates the dominant group velocities, resulting in reduced TBR. This work has important implications on experimental studies, opening up a new space for engineering hybrid nano/microelectronics

Metal Charge Transfer Doped Carbon Dots with Reversibly Switchable, Ultra-High Quantum Yield Photoluminescence

As a class of the heteroatom-doped carbon materials, metal charge-transfer doped carbon dots (CDs) exhibited an excellent optical performance and were widely used as fluorescent probes. To improve fluorescence quantum yield (QY) remains one of the fundamental and challenging issues in the carbon dots field. Herein, we prepared a novel manganese doped CDs (Mn-CDs), which exhibited an ultrahigh quantum yield of 54%, the highest quantum yield for metal-doped CDs. Various spectroscopic measurements revealed an in situ change of dopant oxidation state during the synthesis. Our further study indicated the presence of metal–carbonate, which served as an important component for high quantum yield. We have also studied the reversibly switchable fluorescence property of Mn-CDs by adding Hg²⁺/S^2–, as well as elucidating the underlying mechanism of this switching fluorescence phenomenon. By using the Mn-CDs as fluorescent probes, we developed an extremely sensitive detection method for heavy metal Hg²⁺ detection at a nM detection limit level