超快激光超饱和掺杂微观机制及材料物性研究

Supersaturated doping possesses great potential in the field of the new generation VIS-NIR detectors and the broad-spectrum mid-gap solar cells because of its novel features like deep impurity levels, near metal-insulator transition doping concentrations and extended sub-bandgap absorptions. This project focuses on the unsolved key problems such as microscopic mechanisms of supersaturated doping by femtosecond laser, precise characterizations of hyperdoped materials and optimizations of material performance and proposes the study of femtosecond laser hyperdoped silicon (pink silicon) with smooth surface. Key parameter calculation methods during laser-plasma interactions and phase transitions, as well as techniques of pump-probe detection, transient emission spectra and secondary ion mass spectrometry are to be combined to reveal the physical mechanisms of supersaturated doping and to complete the principle of internal relations and mutual influences between doping elements, preparation conditions, annealing methods and materials' microscopic structure information. Transient optoelectronic technology will be utilized to study the carrier transport mechanism of supersaturated doped silicon for its further controllable theories to establish and improve. Efforts will be made to explore tuning technologies and improving conditions of supersaturated doped black silicon detector's macroscopic properties, which can provide both experimental support and theoretical evidence for the research of new generation silicon-based photoelectric materials and devices.

超饱和掺杂材料具有深能级金属绝缘体相变、扩展子带隙吸收等新颖特性，在新一代可见-红外一体探测器、广谱吸收中间带太阳能电池领域有非常大的潜力。本研究针对目前飞秒激光超饱和掺杂硅材料中未解决的掺杂微观机制、材料细致表征、性能优化等问题，提出研究具有平整表面的飞秒激光超饱和掺杂硅材料（粉硅）。拟采用泵浦探测技术、瞬态发射谱、二次离子质谱等技术，结合激光等离子体及材料相变过程中的关键力学参数计算的方法研究揭示超饱和掺杂的微观机制。揭示掺杂元素、制备条件和退火方式与原子、电子等材料微观结构信息的内在关联和相互影响的规律。利用瞬态光谱技术研究超饱和掺杂材料中载流子输运过程，建立和完善载流子微观输运机制，力求从物理机理出发探索超饱和掺杂硅材料与器件的光电性能调控技术及其优化条件，为发展新一代硅基光电器件提供实验支持与理论依据。

超饱和掺杂材料具有深能级金属绝缘体相变、扩展子带隙吸收等新颖特性，在新一代可见-红外一体探测器、广谱吸收太阳能电池等领域有非常大的潜力。在本项目的研究中，我们利用飞秒激光制备了高质量超饱和掺杂微纳结构黑硅材料与器件，系统研究了飞秒激光参数对超饱和掺杂黑硅材料及其器件的影响，从物理机理出发探索了超饱和掺杂硅材料与器件的光电性能调控技术及其优化条件，在此基础上研制出了高质量的超饱和掺杂黑硅光电探测器，为发展新一代硅基光电器件提供实验支持与理论依据。主要研究包括：1.分析了飞秒激光诱导硅微纳结构表面形貌演变过程，分析证实有效退火能够减少硅纳米颗粒的团簇，修复晶格，减少缺陷，改善材料与器件的光电性能；2.研究了飞秒激光超强超快作用晶体材料的热力学过程，详细分析了激光作用过程中单晶Si的晶相转变。3.系统分析了工艺参数对微纳结构表面形貌、超饱和掺杂浓度、掺杂离子的能级位置、载流子浓度变化等影响，优化了超饱和掺杂黑硅材料与器件的性能；4.完善了TTM-Drude模型，该模型能够系统描述飞秒激光与晶体材料相互作用过程中的载流子和晶格变化，系统模拟分析了飞秒激光与晶体材料的相互作用物理机制；5.利用快速热退火修复缺陷、激活载流子，非晶硅钝化抑制表面态等技术研制出的过饱和掺杂黑硅光电探测器，在400nm到1600nm范围内的响应特性，超出商用硅基探测器大约三个数量级，在1310和1550nm黑硅光电探测器在20V偏压下的响应分别能达到0.58和0.80A/W，达到商用锗探测器红外响应水平，突破了硅基探测器的能带极限。6.提出了利用飞秒激光制备基于超薄单晶硅的柔性黑硅光电探测器，在550nm到1100nm波长范围内弯曲应力对器件的光电响应几乎没有影响，最大比探测率D*值高达1.66×1013Jones。与之前报道的硅基光电探测器相比，黑硅器件展现出更加优异的综合性能。