Instabilities in LEC GaAs Schottky barrier pixel detector imaging arrays

We present room temperature measurements of inhomogeneities and instabiliti es in a GaAs pixel detector array at high bias voltage. The evolution of th e inhomogeneity structure and its change due to increase of bias voltage wa s investigated. The dark current image was analyzed. It is proposed that a cellular structure of higher and lower conductivity regions is responsible for the inhomogeneities and their spatial and temporal instability. The ele ctrical inhomogeneity in LEC SI-GaAs and its dependence on electric field w as qualitatively investigated by using a hybridized GaAs pixel detector and a model of the influence of crystal inhomogeneity on the measured paramete rs of the detector array is proposed. (C) 2001 Elsevier Science B.V. All ri ghts reserved.