Jaiswal Suman, Fathi-Hafshejani Parvin, Yakupoglu Baha, Boebinger Matthew G, Azam Nurul, Unocic Raymond R, Hamilton Michael C, Mahjouri-Samani Masoud
Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849, United States.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
ACS Appl Mater Interfaces. 2023 Aug 23;15(33):39697-39706. doi: 10.1021/acsami.3c06009. Epub 2023 Aug 14.
The interest in the wafer-scale growth of two-dimensional (2D) materials, including transition metal dichalcogenides (TMDCs), has been rising for transitioning from lab-scale devices to commercial-scale systems. Among various synthesis techniques, physical vapor deposition, such as pulsed laser deposition (PLD), has shown promise for the wafer-scale growth of 2D materials. However, due to the high volatility of chalcogen atoms (e.g., S and Se), films deposited by PLD usually suffer from a lack of stoichiometry and chalcogen deficiency. To mitigate this issue, excess chalcogen is necessary during the deposition, which results in problems like uniformity or not being repeatable. This study demonstrates a condensed-phase or amorphous phase-mediated crystallization (APMC) approach for the wafer-scale synthesis of 2D materials. This method uses a room-temperature PLD process for the deposition and formation of amorphous precursors with controlled thicknesses, followed by a post-deposition crystallization process to convert the amorphous materials to crystalline structures. This approach maintains the stoichiometry of the deposited materials throughout the deposition and crystallization process and enables the large-scale synthesis of crystalline 2D materials (e.g., MoS and WSe) on Si/SiO substrates, which is critical for future wafer-scale electronics. We show that the thickness of the layers can be digitally controlled by the number of laser pulses during the PLD phase. Optical spectroscopy is used to monitor the crystallization dynamics of amorphous layers as a function of annealing temperature. The crystalline quality, domain sizes, and the number of layers were explored using nanoscale and atomistic characterization (e.g., AFM, STEM, and EDS) along with electrical characterization to explore process-structure-performance relationships. This growth technique is a promising method that could potentially be adopted in conventional semiconductor industries for wafer-scale manufacturing of next-generation electronic and optoelectronic devices.
从实验室规模的器件向商业规模的系统转变过程中，包括过渡金属二硫属化物（TMDCs）在内的二维（2D）材料的晶圆级生长受到越来越多的关注。在各种合成技术中，物理气相沉积，如脉冲激光沉积（PLD），已显示出在2D材料晶圆级生长方面的潜力。然而，由于硫属原子（如S和Se）的高挥发性，PLD沉积的薄膜通常存在化学计量比不足和硫属元素缺乏的问题。为了缓解这个问题，在沉积过程中需要过量的硫属元素，这会导致诸如均匀性或不可重复性等问题。本研究展示了一种用于二维材料晶圆级合成的凝聚相或非晶相介导结晶（APMC）方法。该方法使用室温PLD工艺进行非晶前驱体的沉积和形成，前驱体具有可控的厚度，随后进行沉积后结晶过程，将非晶材料转化为晶体结构。这种方法在整个沉积和结晶过程中保持了沉积材料的化学计量比，并能够在Si/SiO₂衬底上大规模合成晶体二维材料（如MoS₂和WSe₂），这对于未来的晶圆级电子器件至关重要。我们表明，在PLD阶段，层的厚度可以通过激光脉冲的数量进行数字控制。利用光谱学来监测非晶层的结晶动力学随退火温度的变化。使用纳米级和原子级表征（如原子力显微镜、扫描透射电子显微镜和能谱分析）以及电学表征来探索晶体质量、畴尺寸和层数，以研究工艺 - 结构 - 性能关系。这种生长技术是一种很有前途的方法，有可能在传统半导体行业中用于下一代电子和光电器件的晶圆级制造。
