Novel silicon stripixel detector: concept, simulation, design, and fabrication

Abstract

A novel detector concept has been developed in this work that has the necessary properties to provide two-dimensional (2-D) position sensitivity with a moderate number of readout electronic channels and single-sided detector fabrication process. The concept is based on interleaved pixel electrodes arranged in a projective X– Y readout, which makes possible position encoding with minimum number of channels. In further discussions, we refer to this concept as “stripixel” detector, as it combines the 2-D position resolution of a pixel electrode geometry with the simplicity of the projective readout of a double-sided strip detector. For DC coupled detectors with large pitches (>20 μm), individual pixels are divided into X- and Y-cell that can be interleaved by many different schemes that ensure the charge sharing between them. This type of stripixel detectors is called interleaved stripixel detectors. When the detector pitch goes down (<20 μm), the X and Y-pixel may not have to be interleaved, and they can be connected in an alternating way to X– Y strip readout. This type of stripixel detectors is called alternating stripixel detectors (ASD). For ASD, a position resolution better than 1 μm in two dimensions can be achieved by determining the centroid of the charge collected on pixel electrodes with a granularity in the range of 5–6 μm. For AC coupled detectors, no interleaving scheme may be needed, and there may be no limit on the pitch size, i.e. it may go from pitches in the order of microns, to hundreds of microns or even mm's. This electrode granularity does not pose difficult demands on the lithography and the fabrication technology. This novel detector concept can be applied to any semiconductor detectors/sensors, such as Si, Ge, GaAs, SiC, diamond, etc.