Low gain avalanche detectors for fast timing application
Supervisor: Dr Dima Maneuski and Dr Richard Bates
Industry Partner: Micron Semiconductor Ltd
School: Physics & Astronomy
Description:
Silicon sensors are essential in a range of fields, from cutting-edge research (materials science, particle physics, chemistry) to industry (agriculture, manufacturing), and everyday devices (cameras, security). They serve as the eyes of our electronic world. As scientists develop more precise sensors -such as cameras with smaller pixels -the potential reach of these devices increases, allowing for more detailed investigation of various processes. Currently, the resolution of such sensors is at the micrometre level. However, time precision remains a challenge due to significant technological hurdles in accurately assigning times to signals within the silicon. The best precision achievable for small-pixel silicon sensors is at the nanosecond (ns) level. To put this in perspective, light travels approximately 300,000 micrometres per ns. Unfortunately, our ability to observe many processes is significantly hampered by limitations in time precision.
The Low Gain Avalanche Detector (LGAD) represents a new concept within the Avalanche Photodiode (APD) family, with a gain in the region of 5-10. Unlike a planar silicon detector, the lower gain of LGADs results in an improved signal-to-noise ratio, and they exhibit reduced noise compared to a standard avalanche photodiode. These LGADs can be highly segmented and assembled into hybrid pixel detectors.
This research project aims to build and commission a timing characterisation setup at Glasgow. This setup will be used to test, for the first time, the recently fabricated Trench Isolated LGADs (TI-LGADs)—the third generation of small-pitch pixelated LGADs. These sensors allow simultaneous precise measurements of particle position (within 15 μm) and time (within 50 ps). TI-LGADs are produced by our UK industrial partner, Micron Semiconductor Ltd. Designed for manufacture, these devices feature a simpler fabrication process, allowing for cheaper manufacturing with higher yield, while still offering excellent timing performance and position resolution.
In this work, we propose to build a Minimum Ionising Particle (MIP) test setup, which will study the timing performance of these sensors as a function of temperature. It is essential to examine these devices at various bias voltages and temperatures, as timing performance depends on these factors.
Ultimately, these sensors will open up new fields of research and find broad applications in fundamental research (such as electron microscopy), applied science and industry (particularly in functional materials), and the healthcare sector (specifically in proton therapy).
The intern will work in a team consisting of two academic and industrial supervisors, a PhD student (a former intern from the 2022 EPSRC Vacation Internship program). The intern will be introduced to the topic and undergo essential training related to the equipment to be used, as well as relevant safety aspects when working with radioactive sources and sensitive electronics equipment. Micron Semiconductor Ltd. will allocate an experienced and junior member of staff at their premises in Lancing, UK. The company is willing to host a capable EPSRC vacation intern at their premises for at least a week toward the end of the project. This arrangement will facilitate the transfer of developed capability to the company in the most efficient manner, while also providing the intern with invaluable industrial experience early in their career.
In Glasgow, the intern will work as part of the Glasgow Laboratory for Advanced Detector Development (GLADD), a PPE flagship cleanroom facility. Our experienced technical staff will provide the intern with training and work experience in the state-of-the-art cleanroom facility, further enhancing the applicant’s future employability.
Figure. Ti-LGADs wafer produced by Micron Semiconductors Ltd.
Figure. Sr90 response of a standard LGAD sensor.