GaAs中广延缺陷与载流子输运关联研究

Defects behavior in the semiconductor is an important research topic. In this proposal the influences of extended defects on the carrier transportation in GaAs are detected by photoluminescence (PL) technology. First for the two test modes--U/L mode (uniform illumination/local detection) and the L/L mode (local illumination/local detection), the comparisons of different system spatial resolution and carrier distribution under these two modes can be accomplished by a singlet defect. In theory, the injected light and the singlet defect can be treated as a positive and negative generation source, respectively, then a superposition principle is used to solve the influence of the isolated defect on carrier distribution; and then by means of time-resolved PL technology, the isolated defect evolution verse time is observed. A numerical simulation method is access to obtain the carrier lifetime and diffusion length around the defect. Based on the singlet model, PL technology can be further used to detect the line defect. We hope to establish a model including the effects of illumination, diffusion and defect recombination on carrier distribution. Combined with other measurement methods, such as TEM and Raman spectra, a thorough understanding of extended defects in GaAs, i.e. the morphology, inner structure and evolution, can be founded, which is used to optimize the theoretical model. Theoretical model and PL experimental results under different modes are mutually verified, this process is important to clarify the relationship between carrier concentration change around defects, system spatial resolution and the material parameters of GaAs, which provides a scientific basis for the preparation of high performance semiconductor optoelectronic devices.

半导体中的缺陷是一个重要的研究课题。本项目主要以不同模式的光致发光(PL)技术研究GaAs中广延缺陷对周围载流子输运的影响。首先，在稳态PL的U/L模式(均匀光照/局域探测)和L/L模式(局域光照/局域探测)下，以位错露头来比较两种模式下系统空间分辨率和载流子分布，将注入和缺陷等效为正、负产生，利用叠加原理研究缺陷对载流子空间分布的影响；其次，借助时域PL技术来观察缺陷随时间的演化，结合数值模拟获得缺陷周围的少子寿命、扩散长度；在位错露头模型基础上进一步研究线缺陷，建立注入、扩散共同存在时缺陷复合对载流子分布的影响模型。结合TEM、Raman谱等测试手段研究GaAs中广延缺陷的形貌、结构和演化，修正完善理论模型。理论计算和不同模式下PL实验结果相互验证，阐明GaAs缺陷周围载流子浓度变化与系统空间分辨率、材料特征参数间的联系，为制备高性能半导体光电器件提供科学依据。

半导体中的缺陷是一个重要的研究课题。本项目主要以光致发光技术（PL）和Raman测试来研究GaAs中广延缺陷对周围载流子输运的影响。首先，在不同强度光照下发现广延缺陷的表现并不相同，可借助缺陷的行为提取载流子扩散长度信息。其次，PL测试的不同模式具有不同的空间分辨率，L/L（局域光照/局域探测）模式的空间分辨率是U/L（均匀光照/局域探测）模式下空间分辨率的两倍；而采用Raman测试，由于载流子与GaAs的晶格声子形成声子-等离激元耦合（LOPP），Raman测试的空间分辨率可达L/L模式的10倍。因此，同一个缺陷在Raman模式下表现得更细小、更清晰。结合Raman测试和PL测试，可给出缺陷周围载流子浓度、辐射复合率、非辐射复合率等参数。本项目的重要意义在于借助缺陷研究阐明缺陷表现与测试系统空间分辨率、材料特征参数等息息相关，虽然上述研究只观测了GaAs中的广延缺陷，但研究结果可直接应用于其他半导体材料或器件，如CdTe、GaN、钙钛矿等的缺陷识别和观测中，为高性能的半导体光电器件制备提供科学依据。