  Low Gain Avalanche Detectors (LGADs) are thin silicon detectors with moderate
internal signal amplification and time resolution as good as 17 ps for minimum
ionizing particles. However, the current major limiting factor in granularity
is due to protection structures preventing breakdown caused by high electric
fields at the edge of the segmented implants. This structure, called Junction
Termination Extension (JTE), causes a region of 50-100~\um\ of inactive space.
Therefore, the granularity of LGAD sensors is currently limited to the mm
scale. A solution would be AC-coupled LGADs (AC-LGADs) which can provide
spatial resolution on the 10's of um scale. This is achieved by an un-segmented
(p-type) gain layer and (n-type) N-layer, and a dielectric layer separating the
metal readout pads. The high spatial precision is achieved by using the
information from multiple pads, exploiting the intrinsic charge-sharing
capabilities of the AC-LGAD provided by the common N-layer. TCAD software
(Silvaco and Sentaurus) was used to simulate the behavior of AC-LGADs. A set of
simulated devices was prepared by changing several parameters in the sensor: N+
resistivity, strip length, and bulk thickness.
