太赫兹探测器读出电路的单电子晶体管制备

Fabrication of single electron transistors as the readout circuits for terahertz detectors

摘要:

射频单电子晶体管具有高电荷灵敏度和高读出速率的特点，可用于超导太赫兹单光子探测器产生的微弱电荷信号的读出。采用绝缘体上硅(SOI)材料制备的硅基单电子晶体管具有结构可控、工艺可重复的优点。但是，目前单电子晶体管的成品率约为30%，难以满足探测器阵列化的需求。为进一步提高单电子晶体管成品率，首先采用电子束零宽度线曝光工艺精确设定单电子晶体管的图形，其次对感应耦合等离子体刻蚀工艺中的气氛比例进行优化，实现电子束曝光图形的良好转移。最后通过降低氧化温度进一步保持了图形转移的准确度。单电子晶体管的隧穿势垒宽度得到了良好的控制，使成品率提高到90%，增强了单电子晶体管作为阵列化超导太赫兹单光子探测器读出电路的可行性。

关键词:零宽度线曝光;单电子晶体管;近邻效应;太赫兹单光子探测器;隧穿势垒

Abstract:

Radio-Frequency Single-Electron-Transistor(RF-SET) allows for readout of sub-electron-charge with high speed. Hence，a RF-SET could be used as a readout circuit for superconducting terahertz single-photon detector which converts photons into charges. SETs could be fabricated on Silicon on Insulator(SOI) with good controllability and reproducibility. However, the current yield of SETs on SOI (about 30%) is not yet sufficient for realizing a detector array. In order to improve the yield, single-line exposure mode of Electron-Beam Lithography(EBL) is used to precisely define the width of tunneling barriers; and the etching gas in Inductively-Coupled Plasma(ICP) etching is optimized to realize good pattern transfer; oxidation of silicon is performed at a lower temperature to maintain the precision in the definition of SETs. Since the tunneling barriers are precisely controlled, the yield of SETs has been increased to 90%. Such a high yield makes it more practical to implement SETs as readout circuits in detector arrays.

Key words:Single-line exposure;Single Electron Transistor;proximity-effect;THz single photon detector;tunneling barrier