Staebler-Wronski effect in tritiated amorphous silicon

氢化非晶硅（a-Si:H）是光伏和微电子领域最重要的材料之一。在非晶材料中引入氚（氢的一种同位素），激发了对悬空键缺陷和亚稳态性质的基础研究。1995年，申请人对氚化非晶硅的性质进行了系统的研究。初步研究表明，氚可以永久地结合在非晶硅中，从而使这种放射性物质相对安全。与氚衰变有关的现象为非晶半导体的研究提供了一个非常有力的新工具。特别是，在a-Si:H网络中的氚衰变可以用来模拟和分析Staebler-Wronski （S-W）效应，这是导致a-Si:H光电性能退化的原因。此外，在衰变过程中释放的能量可以被利用并转化为其他有用且无害的能量形式。本提案的主要目标是：更好地了解非晶半导体的物理性质和氚在非晶半导体中的作用。研究将在理论和实验两个层面进行。此外，能源“危机”使“核解决方案”重新回到了最前沿，以CANDU反应堆为基础的加拿大核电站代表了氚气的主要和独特来源。这项研究将导致氚在微电子器件中的发展和安全利用，通过探索氚化非晶半导体的实际应用，包括自供电发光器件和电池，有可能使加拿大工业受益。在5年的时间里，至少有3名最近批准的材料科学硕士项目的硕士生参与研究；一些本科生也将参与暑期项目。学生将接受以下培训：i)使用从头算分子动力学（AIMD）模拟半导体和其他材料的光电特性，ii)执行项目所需的实验测量。

Hydrogenated amorphous silicon (a-Si:H)-represents one of the most important materials in the areas of photovoltaics and microelectronics. The introduction of tritium (an isotope of hydrogen) into amorphous materials has spurred fundamental studies on the nature of dangling bond defects and metastability. In 1995 the applicant initiated a systematic research of the properties of tritiated amorphous silicon. Preliminary studies have shown that tritium can be permanently bonded in amorphous silicon, thereby rendering this radioactive substance relatively safe. Phenomena associated with the decay of tritium offer a very powerful new tool in the study of amorphous semiconductors. In particular, Tritium decay within the a-Si:H network can be used to simulate and analyze the Staebler-Wronski (S-W) effect, which is responsible for the degradation of the opto-electronic properties of a-Si:H. Furthermore, the energy released during the decay can be harnessed and transformed into other, useful and harmless, forms of energy. The main objectives of this proposal are: to achieve a better understanding of the physical properties of amorphous semiconductors and of the effects of tritium in amorphous semiconductors. The research will be conducted at both theoretical and experimental levels. In addition, the energy "crunch" has brought the "nuclear solution" back to the forefront, and the Canadian nuclear plants, based on the CANDU reactor, represent a major and unique source of Tritium gas. This research will lead to the development and to the safe utilization of tritium in microelectronic devices, having the potential to benefit Canadian industry via exploration of practical applications of tritiated amorphous semiconductors, including self-powered light emitting devices and batteries. At least three M.Sc. students in the recently approved Master in Materials Science program will be involved in the research over the course of 5 years; several undergraduate students will also be involved in summer projects. The students will be provided training to: i) use Ab Initio Molecular Dynamics (AIMD) to simulate optoelectronic properties of semiconductors and other materials, ii) perform the experimental measurements required for the project.