能带可调PbSSe微纳结构的可控制备及中红外光学特性研究

Mid-infrared photonic devices are critical important and have been widely used in the fields of military and civilian applications. Small size and high-density integration are required for the future high performance Mid-infrared photonic devices. The semiconductor micro-nano structures, like wires and plates, etc, can act as the gain media and the naturally formed optical micro-cavities, simultaneously, and they thereby are considered as the ideal building blocks for the integrated photonic devices. In this project, we will realize the controllable preparation of full-composition-tunable PbSSe alloy micro-nano structures (band gaps ranges from 0.28 to 0.41 eV), which have excellent mid-infrared emission properties at room temperature. The infrared emission properties will be investigated with home-made infrared emission characterization systems with micron spatial resolution, which will benefit well understanding the energy band structure. Furthermore, the dielectric distributed Bragg reflector micro-cavity will be used to increase the light confinement in PbSSe micro-nano structures, which will help the realization of the stimulated emission with the wavelength tuned from 3.0 to 4.4 micron. The success of this research will provide a new route for the growth of composition tunable semiconductor material with the band gap at mid-infrared light region, which will promote the practical applications of the micro-nano photonic and optoelectronic devices at mid-infrared region.

中红外光子学器件在军事和民用领域均有广泛的应用。小型化、高集成度是未来高性能红外发光器件的发展趋势。半导体微纳结构，如：微纳米线、片等，既可以作为光增益介质，又可以作为天然的光学腔，是理想的可集成光子学器件构成单元。本课题以在室温具有优异发光特性的铅的硫族化合物为研究对象，在本研究组前期对半导体微纳结构可控制备的基础上，进一步实现能带可调PbSSe微纳结构的可控生长，实现带隙在0.28-0.41 eV连续可调。利用自搭建的微区红外测试系统对其中红外发光特性进行系统研究，结合STM表征及理论模拟研究其能带结构与光学特性的关系。借助介质布拉格反射器微腔提高光在PbSSe微纳结构中的限域，减少传输损耗，实现3.0-4.4 μm波长可调谐激光器。本项目的成功实施将为能带可调中红外发光材料提供新的制备和表征方法，促进高性能微纳中红外光子学器件实用化，有助于我国中红外可集成光子学器件领域占领国际前沿。

窄带隙PbX（X=Se, S）是传统的中红外半导体材料。但是其微纳米结构制备技术不成熟及其带隙不连续，红外发光特性研究不充分等问题，这直接影响其实际应用。我们首先系统研究了气相沉积技术实现PbSe及PbSSe微纳结构的制备，成功实现了自催化VLS生长PbSe微米线的技术，结合理论和实验解决了在VLS生长过程中大量VS伴生PbSe微米块的问题，提高了样品形貌的均一性，中红外变温荧光研究表明了PbSe反常的带隙与温度依赖关系；利用能带工程，进一步实现了VLS生长全组分PbSSe微米线，使得发光波长可在2900至4200 nm范围连续可调，为中红外波段光学和光电器件提供了有力材料支撑；通过调控生长条件及衬底，成功实现了在Si衬底上竖立和在MoS2上水平外延生长PbSe纳米片，利用竖立生长的纳米片方便转移的特点，成果实现了将之无损转移至光纤端面，得到了1-2 μm波长范围的稳定锁模输出红外脉冲激光，为脉冲光纤激光的波长调控提供解决方案；在MoS2表面外延的PbSe纳米片被成功应用在红外探测器中；在可控制备PbSe微米线的基础上，同时研究了在其表面外延CsPbBr3壳层结构，提出了自顶端向下扩散的外延生长机制，基于该核-壳异质结构特殊的界面能带排列，实现了近红外至中红外波段的波长依赖的光电响应极性调控；同时，进一步将外延生长理论和技术拓展至CsPbBr3纳米线与Bi2O2Se纳米片混合维度异质结生长中，并且进一步提高了其光电性能。通过该项目的实施，不仅正确理解了中红外半导体材料PbX的微纳结构的可控制备技术和理论，还建立了表征微区中红外发光的装置和技术，同时将相关技术和理论进一步扩展至其它体系，也为本研究小组下一步研究工作奠定了坚实的基础。