Role of the charge state of deep vanadium impurities and associations of defects in photoelectric and optical properties of semi-insulating CdTe crystals
Role of the charge state of deep vanadium impurities and associations of defects in photoelectric and optical properties of semi-insulating CdTe crystals
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DOI：
10.1088/0268-1242/14/1/006
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发表时间：
1999
影响因子：
1.9
通讯作者：
K. Jarašiūnas;L. Bastienė;J. Launay;P. Delaye;G. Roosen
中科院分区：
文献类型：
--
作者：
K. Jarašiūnas;L. Bastienė;J. Launay;P. Delaye;G. Roosen
利用简并四波混频技术研究了块体掺钒和Cl-（或As-）共掺CdTe晶体的光激发载流子和空间电荷场亚纳秒动力学。皮秒光栅衰减在不同光照强度下的时间分辨测量揭示了掺杂或光照下缺陷转变的特点。首次观察到载流子生成和动力学的新特征，并允许提取缺陷的参数。在CdTe:V中观察到快速的电子捕获和随着光照强度的增加而饱和，这归因于Cd距离，这被称为深双受体。利用双深圈闭模型的数值模拟使我们能够提取Cd空位的浓度和重组活性。发现cl共掺杂CdTe:V晶体的电子生成率提高了3-4倍，尽管共掺杂后供体钒态密度降低。我们将这个额外的电子产生通道归因于DX中心的光激发，其激活能为1-1.2 eV，接近YAG:Nd激光器的量子能（eV）。
Photoexcited carrier and space charge field subnanosecond dynamics has been investigated in bulk vanadium-doped and Cl- (or As-) co-doped CdTe crystals by using a degenerate four-wave mixing technique. Time-resolved measurements of picosecond grating decay at various illumination intensities revealed peculiarities of defect transformation with doping or under illumination. Novel features in carrier generation and dynamics were observed for the first time and allowed parameters of the defects to be extracted. A fast electron capture and its saturation with increasing intensity of illumination were observed in CdTe:V and attributed to a Cd divacancy, which is known as a deep double acceptor. Numerical modelling by using the two-deep-trap model allowed us to extract the concentration and recombination activity of Cd divacancies. An enhanced electron generation rate by factor of 3-4 was found in Cl-co-doped CdTe:V crystals in spite of a decreased density of donor vanadium states after the co-doping. We attribute this additional channel of electron generation to photoexcitation of the DX centre, which activation energy of 1-1.2 eV is close to a quantum energy of the YAG:Nd laser used ( eV).