Wei, PengKey Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education, and the Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
Silicon membrane strip photodetectors are fabricated based on thin silicon-on-insulator (SOI) wafers. The thin SOI wafer is realized by exploiting a thinning process on back-side. Such detectors can be implemented in proton-beam position detection because its ultra-thin membrane substrate can reduce beam scattering and offer the considerable advantages of a higher radiation hardness. A p-spray implantation process is typically performed at the silicon surface between the n+-strips in order to insulate them, without requiring an extra photolithographic mask. In this paper, the sources of leakage current in the detector are firstly studied by considering both activation energy and simulation analysis in Silvaco TCAD. While the device is operating below avalanche breakdown voltage, the Shockley-Read-Hall (SRH) process and trap-assisted-tunneling (TAT) process are dominantly contributing in leakage current. The dominant breakdown voltage is attributed to the premature breakdown in the junction of p-spray/n+-region. The shift of this breakdown voltage under repeated avalanche processes is analyzed in-depth by both experiments and simulations, as a function of temperature and electrical stress conditions, which are introducing an important reliability problem. The electrical stress can be attributed to an increase of fixed charge density at the Si/SiO2 interface. The breakdown voltage finally increases by 4 V after successive avalanche breakdowns as function of the applied excess bias voltage beyond breakdown voltage.
Wei, P., Sabri Alirezaei, I., André, N., Zeng, X., Bouterfa, M., Wang, B., Zeng, Y., & Flandre, D. (2021). The Shift of Breakdown Voltage for Silicon Membrane Strip Detectors Resulting from Surface Avalanche. Journal of Applied Physics, 129(21), 214501-214501. https://doi.org/10.1063/5.0049490 (Original work published 2021)