A new silicon drift detector with reduced lateral diffusion

We present a method to reduce the effect of diffusion in the direction transverse to the drift in silicon drift detectors. This is achieved by creating regions of deep p-implant parallel to the drift direction that act as rigid guidelines during the drift of the charge cloud generated by a radiation interaction. The influence of the deep implanted acceptors on the lateral confining field is discussed. A prototype has been designed, fabricated and tested. First experimental results are reported which demonstrate the achieved reduction of the lateral width of the electron cloud with respect to free broadening.