3D Simulations And Modeling Of New Low Capacitance Silicon Pixel Detectors

Silicon detector is one kind of the most universal detector and it is based on medium of silicon. Semiconductor detectors, with excellent performances of fast response, high sensitivity, ease of integration, etc., are widely used in the X-ray detection and high-energy particle detection.Pixel silicon detector is one of the new type s of semiconductor detector. A large area detector can be made by an array of different shapes of the pixel cells. The conventional pixel detectors with anode and cathode electrodes filling the whole cell area due to the larger capacitance. The capacitance is a sensitive paramet er in the operation of a silicon tracking detector, as it directly affects the noise and crosstalk.Signal to noise ratio(S/N) is a key parameter of a high performance detector, reducing the detector noise has been one of the main tasks in detector development. This article provides the basis for designing of electrode shape through 2D simulation. Reasonable designing of electrode shape can not only greatly reduce the effective area of new detectors, but also get uniform distribution of electric potential and electric field.A new low capacitance silicon pixel detector is proposed, which is based on a new electrode geometry with reduced effective electrode area while keeping the sensitive volume unchanged. Meanwhile we use device simulation software(Sentaurus TCAD) to get the 3D models of new low capacitance silicon pixel detectors and simulate the electric potential, electric field, capacitance and full depletion voltages. Then compare with the traditional silicon pixel detectors. The results of simulations and the calculations show that:(1) the new detector structure has a much reduced capacitance(by a factor of 3) as compared to the traditional pixel detectors with the same sensitive volume;(2) the full depletion voltage for the new structure is larger than that of the traditional one due to the small electrode effect;(3) a good balance between the detector capacitance and full depletion voltage will be crucial to the design of an optimum pixel detector. These efforts would provide good advice to the design of actual detectors.