Conductance Fluctuations in Amorphous Silicon

非晶硅的电导波动

• 批准号: 9424277
• 负责人: James Kakalios
• 金额: $ 24万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-07-01 至 1998-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9424277&HistoricalAwards=false
• 关键词: Conductance; Fluctuations; Amorphous; Silicon

9424277 Kakalios The principal aim of this research project is to elucidate and study the physical mechanisms underlying conductance fluctuations in hydrogenated amorphous silicon (a-Si:H). Previous studies of 1/f noise and random telegraph switching noise in a-Si:H in our laboratory suggest that the noise arises from inhomogeneous current filaments whose resistance varies in time, possibly due to the motion of bonded hydrogen inducing bonding rearrangements which alter the defect structure of the material. Amorphous silicon films will be synthesized in an rf plasma-enhanced chemical vapor deposition system at the University of Minnesota, for which the doping level and deposition conditions are systematically varied. The temperature and bias dependence of the random telegraph noise of these films will be investigated to determine if the switching noise arises from current microchannels. The non-Gaussian statistics which characterize 1/f noise will be investigated as the properties of the a-Si:H films are varied. Finally, the long-range disorder at the mobility edge will be characterized by comparing the difference between the thermopower and conductivity activation energies, and will be correlated with the noise behavior as well as with the optical and structural properties of these films. These efforts will significantly improve our understanding of the fluctuation phenomena in a-Si, a technologically important material. %%% Hydrogenated amorphous silicon (a-Si:H) is increasingly used in photovoltaic devices, input scanners, fax machines, photocopiers, and thin-film transistors for flat-panel displays. All of these require the large surface area advantages of amorphous semiconductors. As these electronic devices are made smaller, fundamental electrical noise in the amorphous silicon ultimately limits device performance. An understanding of the microscopic m echanisms responsible for the noise phenomena is therefore crucial if amorphous semiconductors are to achive their technological potential. The principal aim of this research project is to elucidate and study these mechanisms as the properties of the thin-film semiconductor are systematically varied. Previous studies of the electronic noise in hydrogenated amorphous silicon in our laboratory discovered that the noise itself exhibits time-dependent fluctuations, that is, the noise has noise! Studies of the noise of the noise provide important information concerning the degree of electronic disorder and long-range correlations in the material. This research will significantly advance our knowledge of fluctuation phenomena in amorphous silicon in particular, as well as improve our understanding of the physics of non-linear relaxation processes in disordered solids, in general. ***

9424277卡卡利奥斯本研究项目的主要目的是阐明和研究氢化非晶硅(a-Si：H)电导波动的物理机制。我们实验室以前对a-Si：H中的1/f噪声和随机电报开关噪声的研究表明，噪声是由电阻随时间变化的不均匀电流丝引起的，可能是由于键合的氢致成键重排的运动改变了材料的缺陷结构。非晶硅薄膜将在明尼苏达大学的射频等离子体增强化学气相沉积系统中合成，系统地改变掺杂水平和沉积条件。将研究这些薄膜的随机电报噪声的温度和偏置依赖关系，以确定开关噪声是否来自电流微通道。随着a-Si：H薄膜性质的变化，表征1/f噪声的非高斯统计特性将被研究。最后，迁移率边缘的长程无序将通过比较热电势和电导激活能之间的差异来表征，并将与噪声行为以及这些薄膜的光学和结构性质相关联。这些努力将大大提高我们对a-Si中涨落现象的理解，a-Si是一种具有重要技术价值的材料。%氢化非晶硅(a-Si：H)越来越多地用于光伏器件、输入扫描仪、传真机、复印机和平板显示器的薄膜晶体管。所有这些都需要非晶态半导体的大表面积优势。随着这些电子设备变得更小，非晶硅中的基本电噪声最终会限制设备的性能。因此，如果非晶态半导体要实现其技术潜力，对造成噪声现象的微观机制的理解是至关重要的。本研究项目的主要目的是阐明和研究这些机制，因为薄膜半导体的性质是系统地变化的。我们实验室以前对氢化非晶硅中电子噪声的研究发现，噪声本身表现出随时间变化的涨落，即噪声是有噪声的！对噪声噪声的研究提供了有关材料中电子无序程度和长程关联的重要信息。这项研究将极大地提高我们对非晶硅中涨落现象的认识，并从总体上提高我们对无序固体中非线性驰豫过程的物理理解。***