β-Ga_(2)O_(3)晶体本征缺陷诱导的宽带超快光生载流子动力学  

Broadband ultrafast photogenerated carrier dynamics induced by intrinsic defects inβ-Ga_(2)O_(3)

作　　者：王露璇 刘奕彤 史方圆 祁纤雯 沈涵 宋瑛林[2] 方宇 Wang Lu-Xuan;Liu Yi-Tong;Shi Fang-Yuan;Qi Xian-Wen;Shen Han;Song Ying-Lin;Fang Yu(Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application,School of Physical Science and Technology,Suzhou University of Science and Technology,Suzhou 215009,China;School of Physical Science and Technology,Soochow University,Suzhou 215006,China)

机构地区：[1]苏州科技大学物理科学与技术学院,江苏省微纳热流技术与能源应用重点实验室,苏州215009 [2]苏州大学物理科学与技术学院,苏州215006

出　　处：《物理学报》2023年第21期200-206,共7页Acta Physica Sinica

基　　金：国家自然科学基金青年科学基金(批准号:11704273);江苏省自然科学研究基金(批准号:BK20221384);“十四五”江苏省重点学科(批准号:2021135);江苏省研究生科研与实践创新计划(批准号:KYCX22_3267);苏州科技大学大学生创新创业训练计划(批准号:202310332270X,2022011002X)资助的课题.

摘　　要：利用超快瞬态吸收光谱,针对氧化镓(β-Ga_(2)O_(3))晶体中本征缺陷诱导的载流子俘获和复合等动力学进行研究.实验发现,由本征缺陷诱导的宽带吸收光谱具有很强的偏振依赖性,特别是从不同探测偏振下的瞬态吸收光谱中可以提取出两个缺陷态吸收响应.该缺陷诱导的吸收响应归因于从价带到本征缺陷(镓空位)不同电荷态的光学跃迁,利用基于单缺陷的多能级载流子俘获模型拟合得到缺陷俘获空穴的速率远快于俘获电子,且缺陷态的吸收截面相较于自由载流子吸收截面大至少一个数量级.本文的研究结果不仅能明确本征缺陷与光生载流子动力学之间的关系,而且为β-Ga_(2)O_(3)在超快宽带光电子器件中的应用提供科学指导.The ultra-wide bandgap semiconductor gallium oxideβ-Ga_(2)O_(3)with enhanced resistance to the irradiation and temperature is favorable for high-power and high-temperature optoelectronic devices.β-Ga_(2)O_(3)also exhibits great potential applications in the field of integrated photonics because of its compatibility with the CMOS technique.However,a variety of intrinsic and extrinsic defects and trap states coexist inβ-Ga_(2)O_(3),including vacancies,interstitials,and impurity atoms.The defect-related carrier dynamics inβ-Ga_(2)O_(3)not only adversely affect the optical and electrical properties,but also directly limit the performance ofβ-Ga_(2)O_(3)based devices.Therefore,a comprehensive understanding of the carrier transportation and relaxation dynamics induced by intrinsic defects is very important.Supercontinuum-probe spectroscopy can provide a fruitful information about the carrier relaxation processes in different recombination mechanisms,and thus becomes an effective way to study the defect dynamics.In this work,we study the dynamics of carrier trapping and recombination induced by intrinsic defects in pristineβ-Ga_(2)O_(3)crystal by using wavelength-tunable ultrafast transient absorption spectroscopy.The broadband absorption spectra induced by the intrinsic defects are strongly dependent on the polarization of pump pulse and probe pulse.Particularly,two absorption peaks induced by the two defect states can be extracted from the transient absorption spectra by subtracting the absorption transients under two probe polarizations.The observed defect-induced absorption features are attributed to the optical transitions from the valence band to the different charge states of the intrinsic defects(such as gallium vacancy).The data are well explained by a proposed carrier capture model based on multi-level energies.Moreover,the hole capture rate is found to be much greater than that of the electron,and the absorption cross-section of the defect state is at least 10 times larger than that of free carrier.Our

关 键 词：β-Ga_(2)O_(3) 瞬态吸收 缺陷动力学 载流子俘获 

分 类 号：TN304[电子电信—物理电子学]