Timing performance of small cell 3D silicon detectors

Abstract

A silicon 3D detector with a single cell of 50 × 50 µm 2 was produced and evaluated for timing applications. The measurements of time resolution were performed for 90 Sr electrons with dedicated electronics used also for determining time resolution of Low Gain Avalanche Detectors (LGADs). The measurements were compared to those with LGADs and also simulations. The studies showed that the dominant contribution to the timing resolution comes from the time walk originating from different induced current shapes for hits over the cell area. This contribution decreases with higher bias voltages, lower temperatures and smaller cell sizes. It is around 30 ps for a 3D detector of 50 × 50 µm 2 cell at 150 V and -20 • C, which is comparable to the time walk due to Landau fluctuations in LGADs. It even improves for inclined tracks and larger pads composed of multiple cells. A good agreement between measurements and simulations was obtained, thus validating the simulation results. PACS: 85.30.De; 29.40.Wk; 29.40.Gx Work performed in the framework of the CERN-RD50 collaboration.

Radiation-tolerant Silicon Detectors for the LHC Phase-II Upgrade and Beyond: Review of RD50 Activities

“…Therefore the collection of a sufficiently large signal is less affected by trapping and recombination centers formed during irradiation of the device, ensuring very high efficiencies and resolution even at HL-LHC fluences ( Fig.1b) [16,17]. In addition, shorter drift distances, in combination with a high electric field between the electrodes, also lead to faster drift times, which enables timing resolution down to around 75 ps with unirradiated 3D sensors [18]. 3D sensors have already seen use in the insertable barrel pixel layer in the ATLAS inner tracker, and are included in the inner layers of both CMS and ATLAS Phase-II upgrade designs [2,3].…”

“…3D sensors have already seen use in the insertable barrel pixel layer in the ATLAS inner tracker, and are included in the inner layers of both CMS and ATLAS Phase-II upgrade designs [2,3]. Current research in 3D sensors is focusing on small-cell sensors to meet future requirements for finer granularity in vertexing detectors, and to improve the understanding signal formation and properties for different particle track angles especially in highly-irradiated sensors [17,18,19].…”

LGAD and 3D as timing detectors

“…In part, these are caused by the geometry of the pads themselves [29]. Although the biggest issue are the 40-100 µm-wide no-gain regions due to junction termination structures [30]. Therefore, the next logical step is to produce segmented LGADs.…”

“…In fact, 3D devices with small cell sizes can work up to fluences of the order of 10 16 n eq /cm 2 [33,34]. Another benefit of 3D sensors is their close to 100 % fill factor, a great advantage when compared to pad sensors [30]. All of these properties, specially so the fill factor, the radiation hardness, and the short drift times make 3D sensors a promising technology for timing applications in high radiation environments.…”

Irradiated Single Crystal Chemical Vapor Deposition Diamond Characterized with Various Ionizing Particles

“…An interesting trend in the development toward radiation hard diamonds are 3D‐sensors, where the charge is read out trough graphite pillar electrodes embedded in the crystal . It is promising for tracking applications; however, the 3D detectors tend to suffer from increased jitter in the time of arrival, which makes it less attractive for time‐of‐flight detector applications. Another approach toward radiation hard diamond detectors has been to reduce the thickness of the diamond crystal.…”