基于AlGaN/GaN场效应晶体管的太赫兹焦平面成像传感器

Terahertz focal plane imaging array sensor based on AlGaN/GaN field effect transistors

太赫兹波成像技术在人体安检、医学成像、无损检测等领域具有广泛的应用前景。文中面向高速、高灵敏度和便携式太赫兹成像应用需求,设计实现了一种基于AlGaN/GaN高电子迁移率晶体管自混频检测机制的太赫兹焦平面成像传感器。该焦平面成像传感器由探测器阵列芯片和CMOS读出电路通过倒装互连实现,阵列规模达到32×32。探测器阵列中具有对管差分功能的像元设计通过提高探测器的电压响应度和抑制共模电压噪声,提高了焦平面成像的灵敏度。焦平面成像传感器的输出模拟信号通过片外的模数转换(ADC)芯片转化为数字信号,由现场可编程门阵列(FPGA)采集后通过Camera Link图像数据与通信接口发送到计算机。利用该焦平面成像传感器,演示实现了太赫兹光斑、太赫兹干涉环和太赫兹光照下的旋转塑料叶片的视频成像,帧频达到30 Hz。

Terahertz technologies are believed to find various applications such as security screening,medical imaging,nondestructive inspection etc.For high speed,high sensitivity,and portable terahertz imaging applications,Terahertz Focal Plane Arrays(THz-FPAs)were designed and demonstrated based on self-mixing mechanism in AlGaN/GaN high-electron-mobility transistors(HEMT).The THz-FPAs with an array size of 32×32 were realized by flip-chip bonding a detector array and a readout integrated circuit(ROIC)based on silicon CMOS technology.Each pixel detector consisted of two HEMTs which were configured in a differential output scheme so as to enhance the voltage responsivity,reject the common-mode voltage noise,and increase the sensitivity.The differential detector signals were amplified in the ROIC and converted to digital data by an Analog-to-Digital Converter(ADC)in a printed-circuit board(PCB)which also hosted a Field-Programmable Gate Array(FPGA)for data acquisition and conversion.The data converted into a video stream was sent to a personal computer through the Camera Link interface.The focal plane array was used to demonstrate imaging of terahertz beam spot,terahertz interference ring pattern,and a rotating plastic blade under terahertz illumination all with a frame rate up to 30 Hz.