Localized Electronic States in Amorphous Semiconductors

9704946泰勒这是一个研究无序半导体的电子和结构性质的更新项目。这项研究将回答有关低硫化物浓度的第四类硫化物玻璃和高金属浓度的金属硫化物玻璃的结构、缺陷和掺杂机制的问题。这项研究的第二个重要组成部分将回答有关硫化物玻璃中光致顺磁性和光变暗的微观起源的问题，特别是上述两个模型系统中的问题。科学方法涉及一个基础广泛的计划，该计划利用了几种生长技术、磁共振光谱、光学光谱、光学和磁共振技术的各种组合以及电学测量。具体的目标是(1)了解局域有序的细节，(2)研究作为平均配位数函数的本征缺陷及其相关的亚稳态，以及(4)识别导致光变暗的缺陷。%这是对非晶态半导体继续研究的更新建议。非晶态半导体为许多电子应用提供了晶态半导体的廉价替代品。一个重要的例子是在个人电脑和平板电视屏幕的平板显示器中使用非晶硅作为开关(薄膜晶体管)。这些材料的使用受到当前制造的各种电子或光学设备中随时间发生的变化的阻碍。这项研究中获得的信息将极大地增加我们对电子作为电流载体的行为的理解。这一信息将证实或驳斥已开发的适用于所有非晶态半导体的特定模型。例如，半导体最重要的特性是，通过一种称为掺杂的过程，能够显著改变电导率，这使它们成为电力开关。这项研究将使人们对非晶态半导体的掺杂机制有更全面的了解--这一认识最终可用于制造更可靠的器件。***

9704946 Taylor This is a renewal project for the study of the electronic and structural properties of disordered semiconductors. This research will answer questions concerning the structure, defects and doping mechanisms in Group IV chalcogenide glasses at low chalcogen concentrations and in metal chalcogenide glasses at high metal concentrations. A second important component of the research will answer questions concerning the microscopic origins of optically- induced paramagnetism and of photodarkening in chalcogenide glasses, especially those in the two model systems mentioned above. The scientific approach involves a broadly based program that utilizes several growth techniques, magnetic resonance spectroscopy, optical spectroscopies, various combinations of optical and magnetic resonance techniques, and electrical measurements. The specific objectives are (1) to understand details of the local order, (2) to study the intrinsic defects, and their associated metastabilities, as a function of average coordination number, and (4) to identify the defects that contribute to photodarkening. %%% This is a renewal proposal for a continuing study of amorphous semiconductors. Amorphous semiconductors provide inexpensive alternatives to crystalline semiconductors for many electronic applications. One important example is the use of amorphous silicon for the switches (thin-film transistors) in flat-panel displays for personal computers and flat television screens. The use of these materials is hindered by changes that occur with time in the various electronic or optical devices that are currently manufactured. The information gained in this research will greatly increase our understanding of the behavior of electrons which are the carriers of electrical current. This information will confirm or refute specific models that have been developed to apply generally to all amorphous semiconductors. For example, the most important property of semiconductors that mak es them useful as switches of electricity is the ability to change the electrical conductivity dramatically via a process known as doping. This research will result in a more general understanding of doping mechanisms in amorphous semiconductors - an understanding that can eventually be used to manufacture more reliable devices. ***