横向阵列结构肖特基结辐照电池设计

发布时间：2018-06-28 18:01

本文选题：碳化硅 + 辐照电池　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：近些年来,由于微机电系统的出现使人们对体积小、能够长时间稳定提供电能的电池的需求越来越迫切。传统类型的电池因其各自的局限性无法很好满足需求,而辐照电池的出现有望从根本上解决这一问题。在所有类型辐照电池中,碳化硅(SiC)基辐照电池因其独特的优势而受到很大的重视。碳化硅与硅材料相比,其禁带宽度远大于前者,并且还具有较高的热稳定性、热导率以及载流子饱和速率。此外,碳化硅自身具备优良抗辐照特性,这也使其成为制造辐照电池的首选材料。本文首先对现有的辐照电池的研究成果进行了深入分析研究,在此基础上归纳出提高辐照电池性能的主要方法。当前对辐照电池性能的改进措施主要集中在辐照源的选取、电极的设计以及器件表面结构的创新三个方面。首先,通过选取具有更高能量及更长半衰期的辐照源以获得更多辐照粒子来激发更多的电子-空穴对;其次,通过采用巧妙的电极设计来减小金属电极对辐照粒子的阻挡作用使得更多粒子能够进入换能结;另外,利用在器件表面制作三维结构的方式来增加器件的辐照接触面积以提高对辐照粒子的吸收效率。这些技术手段都可以提升电池的性能,其中以采用三维表面结构形式的辐照电池性能提升最为明显。然而,即便是采用三维表面结构的辐照电池也无法解决辐照粒子吸收效率低这一根本问题。通过对这类电池结构上的共性研究发现该类型辐照电池都采用了纵向的换能结分布结构,即换能结与中性区沿垂直于器件表面方向分布。这样中性区和金属电极会遮挡掉很大一部分的辐照粒子导致实际进入电池内部的辐照粒子非常少,因此降低了对辐照粒子利用率低。这种结构的固有缺陷严重制约了电池性能的提高。本文针对这一问题提出了一种基于肖特基结的横向分布辐照电池,其中性区与换能结平行器件表面呈横向阵列排布。通过这一结构创新可有效解决传统纵向结构辐照电池中性区对辐照的遮挡问题,辐照粒子的利用率得以大幅度的提高,在不改变辐照源的情况下辐照电池的转换效率和输出功率也会得到大幅度的提升。本文在给出电池设计结构的基础上,进一步通过模拟仿真得到了辐照粒子的入射分布情况进而得到电池外延层厚度及金属沟槽深度;通过模拟离子注入及肖特基接触计算得出电极间距等结构参数;此外,通过对碳化硅欧姆接触及掺杂相关成果的研究总结,给出了辐照电池各个区域掺杂浓度以及欧姆接触制作方法。本文最后在参考SiC器件制造工艺基础上结合横向阵列辐照电池的结构特点以及结构参数给出了一套完整的工艺制备流程。工艺流程中在外延层上进行沟槽刻蚀是本流程的核心部分,制造这一结构的电池要求具有较好的刻蚀粗糙度,刻蚀工艺在整个制备流程中具有很高的重要性。通过设置实际的刻蚀对照实验得出了刻蚀SiC最佳的工艺方法和条件,为这一新结构辐照电池的成功制造探索出可行的工艺条件。本文也存在一定的不足,由于SiC光刻工艺的限制未能实现样品的制备不能进行实际的测试。针对这一问题可以考虑将肖特基结换为pn结,这样做的好处在于可有效提高欧姆电极的间距满足光刻工艺分辨率的要求。这种方案要制作出p型欧姆接触,需要解决p型欧姆接触比接触电阻高的问题。
[Abstract]:In recent years, due to the emergence of microelectromechanical systems, the demand for batteries that can provide electrical energy for a long time is becoming more and more urgent. Traditional types of batteries can not meet the needs of their respective limitations, and the emergence of irradiated batteries is expected to solve this problem fundamentally. In all types of irradiated batteries, carbon Silicon carbide (SiC) based irradiated batteries have been paid great attention because of their unique advantages. Compared with silicon materials, silicon carbide has a far greater gap width than the former, and has high thermal stability, thermal conductivity and carrier saturation rate. In addition, silicon carbide itself has excellent radiation resistance, which makes it the first to manufacture irradiated batteries. On the basis of this, the main methods to improve the performance of irradiated batteries are summarized. The current improvement measures for the performance of irradiated batteries are mainly focused on the selection of radiation sources, the design of the electrodes and the innovation of the surface structure of the devices. First, the three aspects. By selecting more irradiated sources with higher energy and longer half-life to obtain more irradiated particles to stimulate more electron hole pairs; secondly, by using the ingenious electrode design to reduce the barrier effect of metal electrodes to irradiated particles, more particles can enter the transition junction; in addition, a three-dimensional structure is made on the surface of the device. In this way, the radiation contact area of the device is increased to improve the absorption efficiency of the irradiated particles. These techniques can improve the performance of the batteries, in which the performance of the irradiated cells in the form of three-dimensional surface structure is most obvious. The basic problem of low efficiency is that this type of battery structure has been studied in general. It is found that this type of irradiated battery adopts a longitudinal commutation junction structure, that is, the commutation junction and the neutral zone are perpendicular to the surface direction of the device. So the neutral and metal electrodes will block out a large portion of the irradiated particles and lead to the actual entry. The irradiated particles inside the battery are very small, so the utilization rate of the irradiated particles is lower. The inherent defect of this structure seriously restricts the performance of the battery. In this paper, a transverse distribution irradiated battery based on the Schottky junction is proposed, in which the surface of the parallel device surface is arranged in a transverse array. This structural innovation can effectively solve the shielding problem of radiation in the neutral zone of the radiation battery of the traditional longitudinal structure. The utilization rate of irradiated particles can be greatly improved. The conversion efficiency and output power of the irradiated battery will be greatly improved without changing the irradiation source. The incident distribution of irradiated particles is obtained by simulation, and the thickness of the epitaxial layer and the depth of metal groove are obtained. The structure parameters such as the electrode spacing are calculated by simulating ion implantation and Schottky contact. In addition, the radiation electricity is given through the study of the results of the ohmic contact and doping related to the silicon carbide. In this paper, a complete process preparation process is given on the basis of the structure characteristics and structural parameters of the transverse array irradiated cell based on the SiC device manufacturing process. The battery of this structure requires a good etching roughness and the etching process is of great importance in the whole preparation process. By setting the actual etching control experiment, the best process and conditions for etching SiC are obtained, and the feasible process conditions are explored for the successful fabrication of this new structure irradiated battery. A certain shortage, because of the limitation of the SiC lithography process, the preparation of the sample can not be tested. The Schottky junction can be replaced by the PN junction for this problem. The advantage of this is that the distance between the ohm electrode and the photolithography resolution can be improved effectively. This scheme needs to produce the P type ohmic contact. It is necessary to solve the problem of high ohmic contact ratio of P type.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM910.2

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