A novel horizontal push-pull multi-substrate epitaxy boat with three separate cells is introduced in this article, with which multi-substrate LPE processing is feasible in horizontal LPE furnace. The processes of LPE ...A novel horizontal push-pull multi-substrate epitaxy boat with three separate cells is introduced in this article, with which multi-substrate LPE processing is feasible in horizontal LPE furnace. The processes of LPE AlxGa1-x)As/ GaAs solar cells are studied and the efficiency of the solar cells achieved 19.8% (AMO, 25℃, 120 mW/cm2).展开更多
利用二维动力学模型,通过变化MOCVD(metal organic chemical vapor deposition)反应器的进气流量、操作压力、衬底温度、基座旋转等几个重要工艺控制参数,计算了反应器内部均匀的流场和热场分布的形态变化,描述了输运过程中产生的多种...利用二维动力学模型,通过变化MOCVD(metal organic chemical vapor deposition)反应器的进气流量、操作压力、衬底温度、基座旋转等几个重要工艺控制参数,计算了反应器内部均匀的流场和热场分布的形态变化,描述了输运过程中产生的多种流动现象,并给出了相应的分析与说明.在此基础上,通过微扰反应器的进气量,计算并图形化了质量输运过程的瞬态行为,分析了延迟时间、驰豫振荡、自脉动振荡等瞬态现象产生的原因,为高品质外延生长工艺的设计与实施,提供了有益的解决途径.展开更多
We report on a Te-seeded epitaxial growth of ultrathin Bi2Te3 nanoplates (down to three quintuple layers (QL)) with large planar sizes (up to tens of micrometers) through vapor transport. Optical contrast has be...We report on a Te-seeded epitaxial growth of ultrathin Bi2Te3 nanoplates (down to three quintuple layers (QL)) with large planar sizes (up to tens of micrometers) through vapor transport. Optical contrast has been systematically investigated for the as-grown Bi2Te3 nanoplates on the SiO2/Si substrates, experimentally and computationally. The high and distinct optical contrast provides a fast and convenient method for the thickness determination of few-QL Bi2Te3 nanoplates. By aberration-corrected scanning transmission electron microscopy, a hexagonal crystalline structure has been identified for the Te seeds, which form naturally during the growth process and initiate an epitaxial growth of the rhombohedral- structured Bi2Te3 nanoplates. The epitaxial relationship between Te and Bi2T% is identified to be perfect along both in-plane and out-of-plane directions of the layered nanoplate. Similar growth mechanism might be expected for other bismuth chalcogenide layered materials.展开更多
Understanding the structural characteristics and growth mechanism(s) are essen-tial for generating core-shell nano-heterostructures with distinctive properties. Especially in lanthanide-based nanocrystals, rational ...Understanding the structural characteristics and growth mechanism(s) are essen-tial for generating core-shell nano-heterostructures with distinctive properties. Especially in lanthanide-based nanocrystals, rational design of the core-shell composition can be utilized to enhance/tune the optical properties of the final nanostructure, or can be used to integrate multiple functional applications (e.g., luminescent/magnetic). In this article, we review the progress in our current understanding of the epitaxial shell growth in sodium lanthanide fluoride (NaLnF4) nanocrystals. In order to understand epitaxial shell growth the core nanocrystals have to be uniform, and to date the synthesis of high quality near uniform size/shape dispersion controlled synthesis of lanthanide-based nanocrystals has been achieved mainly with this class of nanocrystals. The progress in core-shell synthesis and the epitaxial shell growth mechanism in this class of nanocrystals (NaLnF4) are reviewed, and a general perspective is provided on the core-shell morphology based on different characterization techniques. While there has been tremendous progress in studying the impact of core-shell structures in various functional applications, this review also highlights, in our view, the still limited understanding of ways to control the core-shell morphology and it emphasizes some important, unanswered questions that remain to be addressed to maximize their performance.展开更多
Well-aligned single-crystal nanowire arrays of CH3NH3PbIs have shown potentials in laser sources and photovoltaic applications.Here we developed a solution based epitaxial method to grow CH3NH3PbI3nanowire arrays.By c...Well-aligned single-crystal nanowire arrays of CH3NH3PbIs have shown potentials in laser sources and photovoltaic applications.Here we developed a solution based epitaxial method to grow CH3NH3PbI3nanowire arrays.By confining the precursor solution between a silicon wafer and ST-cut quartz,the evaporation rate of the solvent was slowed down which brings a more stable and controllable solution environment.Relying on the lattice match between CH3NH3PbI3 and ST-cut quartz,arrays of single-crystal nanowires of CH3NH3PbI3have been grown epitaxially.The densities and lengths of CH3NH3PbI3 nanowires can be tuned. The lengths of the resultant crystals range from several microns to over one millimeter.Such CH3NH3PbI3arrays with good alignment and crystallinity were then applied to fabricate photovoltaic devices with good performances.展开更多
文摘A novel horizontal push-pull multi-substrate epitaxy boat with three separate cells is introduced in this article, with which multi-substrate LPE processing is feasible in horizontal LPE furnace. The processes of LPE AlxGa1-x)As/ GaAs solar cells are studied and the efficiency of the solar cells achieved 19.8% (AMO, 25℃, 120 mW/cm2).
文摘利用二维动力学模型,通过变化MOCVD(metal organic chemical vapor deposition)反应器的进气流量、操作压力、衬底温度、基座旋转等几个重要工艺控制参数,计算了反应器内部均匀的流场和热场分布的形态变化,描述了输运过程中产生的多种流动现象,并给出了相应的分析与说明.在此基础上,通过微扰反应器的进气量,计算并图形化了质量输运过程的瞬态行为,分析了延迟时间、驰豫振荡、自脉动振荡等瞬态现象产生的原因,为高品质外延生长工艺的设计与实施,提供了有益的解决途径.
文摘We report on a Te-seeded epitaxial growth of ultrathin Bi2Te3 nanoplates (down to three quintuple layers (QL)) with large planar sizes (up to tens of micrometers) through vapor transport. Optical contrast has been systematically investigated for the as-grown Bi2Te3 nanoplates on the SiO2/Si substrates, experimentally and computationally. The high and distinct optical contrast provides a fast and convenient method for the thickness determination of few-QL Bi2Te3 nanoplates. By aberration-corrected scanning transmission electron microscopy, a hexagonal crystalline structure has been identified for the Te seeds, which form naturally during the growth process and initiate an epitaxial growth of the rhombohedral- structured Bi2Te3 nanoplates. The epitaxial relationship between Te and Bi2T% is identified to be perfect along both in-plane and out-of-plane directions of the layered nanoplate. Similar growth mechanism might be expected for other bismuth chalcogenide layered materials.
文摘Understanding the structural characteristics and growth mechanism(s) are essen-tial for generating core-shell nano-heterostructures with distinctive properties. Especially in lanthanide-based nanocrystals, rational design of the core-shell composition can be utilized to enhance/tune the optical properties of the final nanostructure, or can be used to integrate multiple functional applications (e.g., luminescent/magnetic). In this article, we review the progress in our current understanding of the epitaxial shell growth in sodium lanthanide fluoride (NaLnF4) nanocrystals. In order to understand epitaxial shell growth the core nanocrystals have to be uniform, and to date the synthesis of high quality near uniform size/shape dispersion controlled synthesis of lanthanide-based nanocrystals has been achieved mainly with this class of nanocrystals. The progress in core-shell synthesis and the epitaxial shell growth mechanism in this class of nanocrystals (NaLnF4) are reviewed, and a general perspective is provided on the core-shell morphology based on different characterization techniques. While there has been tremendous progress in studying the impact of core-shell structures in various functional applications, this review also highlights, in our view, the still limited understanding of ways to control the core-shell morphology and it emphasizes some important, unanswered questions that remain to be addressed to maximize their performance.
基金supported by the National Natural Science Foundation of China (21631002, U1632119, 21621061, and 91633301) Ministry of Science and Technology of the People’s Republic of China (2016YFA0201904)
文摘Well-aligned single-crystal nanowire arrays of CH3NH3PbIs have shown potentials in laser sources and photovoltaic applications.Here we developed a solution based epitaxial method to grow CH3NH3PbI3nanowire arrays.By confining the precursor solution between a silicon wafer and ST-cut quartz,the evaporation rate of the solvent was slowed down which brings a more stable and controllable solution environment.Relying on the lattice match between CH3NH3PbI3 and ST-cut quartz,arrays of single-crystal nanowires of CH3NH3PbI3have been grown epitaxially.The densities and lengths of CH3NH3PbI3 nanowires can be tuned. The lengths of the resultant crystals range from several microns to over one millimeter.Such CH3NH3PbI3arrays with good alignment and crystallinity were then applied to fabricate photovoltaic devices with good performances.