Kim Min Seok, Lee Gil Ju, Kim Hyun Myung, Song Young Min
School of Electrical Engineering and Computer Science (EECS), Gwangju Institute of Science and Technology (GIST), 123, Chemdangwagi-ro, Buk-gu, 61005 Gwangju, Korea.
Sensors (Basel). 2017 Aug 2;17(8):1774. doi: 10.3390/s17081774.
Curved image sensors, which are a key component in bio-inspired imaging systems, have been widely studied because they can improve an imaging system in various aspects such as low optical aberrations, small-form, and simple optics configuration. Many methods and materials to realize a curvilinear imager have been proposed to address the drawbacks of conventional imaging/optical systems. However, there have been few theoretical studies in terms of electronics on the use of a lateral photodetector as a flexible image sensor. In this paper, we demonstrate the applicability of a Si-based lateral phototransistor as the pixel of a high-efficiency curved photodetector by conducting various electrical simulations with technology computer aided design (TCAD). The single phototransistor is analyzed with different device parameters: the thickness of the active cell, doping concentration, and structure geometry. This work presents a method to improve the external quantum efficiency (EQE), linear dynamic range (LDR), and mechanical stability of the phototransistor. We also evaluated the dark current in a matrix form of phototransistors to estimate the feasibility of the device as a flexible image sensor. Moreover, we fabricated and demonstrated an array of phototransistors based on our study. The theoretical study and design guidelines of a lateral phototransistor create new opportunities in flexible image sensors.
曲面图像传感器是仿生成像系统的关键部件，因其能在诸如低光学像差、小尺寸和简单光学配置等多个方面改进成像系统而受到广泛研究。为解决传统成像/光学系统的缺点，人们提出了许多实现曲线成像器的方法和材料。然而，关于将横向光电探测器用作柔性图像传感器，在电子学方面的理论研究却很少。在本文中，我们通过使用技术计算机辅助设计（TCAD）进行各种电学模拟，证明了基于硅的横向光电晶体管作为高效曲面光电探测器像素的适用性。对单个光电晶体管进行了不同器件参数的分析：有源单元的厚度、掺杂浓度和结构几何形状。这项工作提出了一种提高光电晶体管的外部量子效率（EQE）、线性动态范围（LDR）和机械稳定性的方法。我们还以矩阵形式评估了光电晶体管的暗电流，以估计该器件作为柔性图像传感器的可行性。此外根据我们的研究制作并展示了一个光电晶体管阵列。横向光电晶体管的理论研究和设计指南为柔性图像传感器创造了新机遇。
