Optical and electrical crosstalk in pin photodiode array for medical imaging applications

Optical and electrical crosstalk are the parameters of photodetector arrays for medical imaging applications that often require special attention of the system developers and researchers. This paper studies optical and electrical crosstalk for the back-illuminated, thin pin photodiode arrays built on 75- mum and 100- mum thickness single silicon dies. The features of the arrays include high quantum efficiency, fast signal rise time, very small AC and DC electrical crosstalk (~ 0.01%) within the spectral range 400 to 800 nm. The paper compares the noise performance and detectivity of back-illuminated photodiode arrays with isolating diffusion between pixels and conventional arrays with no isolation between pixels. Different sources of optical crosstalk in scintillator-based X-ray imaging applications are discussed for two types of arrays. The noise characteristics and detectivity for the detector arrays with optical and electrical crosstalk were estimated to be 3-5 times better for the arrays with isolating diffusion than for the conventional photodiode arrays. A brief comparison with the front-illuminated arrays is also provided.