【作者】 王帅；

【导师】 李春；

【作者基本信息】 电子科技大学 ， 工程硕士（专业学位）， 2017， 硕士

【摘要】 光电探测器被广泛的应用在我们的日常生产生活中。目前在可见光波段,光电探测器所用的最主要的材料还是硅,但为了实现特定功能,如拓展、改变探测范围,需要硅与其他材料结合。但值得注意的是,三维材料之间因为存在晶格失配的问题,很难大面积集成。近年来,二维材料持续吸引着人们的目光,特别是石墨烯和过渡金属硫化物（TMDCs）。二维材料有着一些共同的特性:分子在层内由共价键连接,层间由范德华力结合。另外,二维材料没有表面悬挂键的特性,使得分离此种材料变得简单,同时很容易与其他材料进行复合制作异质结结构。特别值得注意的是TMDCs拥有较为理想的禁带宽度（1.06-2.88 eV）,这就使其可以作为光的吸收层用到可见光探测领域,特别是用于高响应度、低功耗、柔性器件中。众所周知,光电二极管是光电探测器的基本结构之一,利用TMDCs材料制作二极管结构的研究可以分成两种:TMDCs-TMDCs（2D-2D）、TMDCs-传统材料（2D-3D）。这里我们重点研究石墨烯/硅、过渡金属硫化物/硅两种异质结结构的制作及性能。首先本文利用二维材料生长和湿法刻蚀的方式制作了Si/Graphene肖特基结,并研究了此肖特基结的光电特性,以及在不同温度下的二极管性能,发现其光响应度达0.5 A/W,响应时间为164μs,具有较好的光电特性。在对其进行温度测试时,我们发现器件在低温下存在反向击穿现象,通过后期实验的对比也对此作出了解释。其次文章通过改进制作工艺,弃除湿法刻蚀的步骤,利用半导体工艺兼容的方式制作了n-Si/WS₂同型异质结结构,并对其光电特性、温度特性以及光电流产生位置问题做了系统的研究。器件同样具有较好的光电特性:光响应度达1.2 A/W,最短响应时间为8μs。且由于改进制作工艺的原因,器件在低温环境中不再出现反向击穿电流。在对光电流产生位置的研究中,通过光电流mapping的测量,我们发现如果外加电压较大,在非异质结区仍然会有较大的光电流产生,本文对此现象也做出了解释。另外本文还研究了量子点修饰对器件光响应的影响,发现通过旋涂碳量子点可以在各个波段提高器件的响应度。最后通过制作更为常见的p-Si/WS₂异质结结构对器件击穿特性做了重点研究。并发现在齐纳击穿点附近器件光响应达到5.6 A/W。本文为研究硅基二维材料集成器件奠定了一定的基础。更多还原

【Abstract】 Photodetector is widely used in our production and daily life.In visible light,the main material for photodetector is silicon.However,in order to achieve some specific functions,such as expanding the detection range,we need other materials combining with silicon.But it is difficult for other 3D materials to integrate with silicon.In the past few years,graphene and transition metal dichalcogenides（TMDCs）has attracted tremendous interest because of their exotic electrical and optoelectrical properties.These two-dimensional（2D）crystals share the common feature with the intra-layer covalent bond and inter-layer van der Waals bond.The lack of surface dangling bonds not only allows them to be easily stripped down to atomic-scale thickness but also can be readily integrated into any other substrates.Especially,most of TMDCs have small band gaps（1.06-2.88 eV）.Therefore,those TMDCs can be used as visible light absorbers for photodetecting application.It is known that junction-based photodiode is one kind of important photodetectors.For TMDCs-related planar structure photodetectors,there are two categories,one is TMDCs-TMDCs（2D-2D）and the other is TMDCs-conventional materials（2D-3D）.Here,we report the fabrication and photoreponse properties of n-Si/Graphene and n-Si/WS₂ heterojunction photodiode.Firstly,we fabricated a n-Si/Graphene Schottky junction using wet etching.Then we studied the photoelectric properties and the I-V curve at different temperatures of the Schottky junction.We found that our device show great properties: photoresponse0.5 A/W,and responsetime 164 μs.Besides our device appeared breakdown at low temperature.The explanation was given through the contrast experiment.Secondly,improving the production technology,discarding the wet etching steps,we fabricated the n-Si/WS₂ heterojunction structure,and studied its photoelectric and temperature properties: photoresponse 1.2 A/W,and responsetime 8 μs.Because of the improvement of fabrication process,this device no longer appear breakdown.Then we focused on the study of the origin of high photocurrent.We found that if the applied voltage was large enough,the non heterojunction region still had a large photocurrent,but its responsetime was slower than the heterojunction region.Besides,we studied the performance of our device with modified carbon quantum dots.The device showed improving photoresponse in each wavelength.At last,we fabricated p-Si/WS₂ heterojunction for studying the breakdown characteristics.And it was found that the photo response of the device was about 5.6A/W,near the zener breakdown point.更多还原