FeTe-SrTiO3 异质结的光电性能研究

  半导体产业是我国当下的产业升级规划中至关重要的一环，其中光电二极管是半导体领域中关系到国防、医疗、工业自动控制以及光电计量等行业的重要组成部件。相比于传统p-n结二极管，基于二维范德华异质结的肖特基光电二极管具有快速响应、高探测率等优点，具备广阔的研究前景。过去的研究中肖特基探测器往往受制于表面态、悬挂键等因素而具备较大的反向漏电流，而无法实现高信噪比探测，因此开发具有良好二维特性的肖特基二极管很有必要。

  本文主要基于分子束外延技术，制备高质量外延FeTe薄膜，探究FeTe薄膜的厚度与外延衬底（SrTiO₃）掺杂浓度两大因素对异质结光电效应的影响，寻求优化该异质结光电效应的方向。实验结果表明，在一定范围内FeTe薄膜的厚度对于入射光的吸收影响不大，当FeTe厚度小于15 nm时，入射光都可以照射到异质结区域，器件可以在一到几个原子层内具备良好的二维特性。在探究半导体衬底的掺杂浓度对光电效应的影响时发现，掺杂浓度变大时，器件的光谱吸收边会红移，低掺杂浓度（0.05%）的衬底外延的器件具备短波和长波两个区域的吸收边。测试FeTe薄膜的紫外光电子能谱时发现其功函数相比前人的研究结果偏大，达到4.9 eV，但可以与外延衬底形成良好的肖特基接触。在一定波长入射光照射下，低掺杂浓度的衬底外延的FeTe薄膜形成的异质结相比高掺杂浓度的衬底（0.5%、0.7%）外延的异质结具备更稳定的光电流，且响应度更显著，达到了1.8×10^-2 A/W，表明衬底的掺杂浓度对于器件的光电效应有影响。

     本文通过对FeTe薄膜与衬底SrTiO₃形成的异质结的光电效应的研究探索了优化该异质结光电性能的方向，并且实现了对单层FeTe薄膜异质结的光电流探测，确认了其具备肖特基探测器应用潜力，为该器件在光电探测领域的研究奠定了基础。

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