Development of a highly pixelated direct charge sensor, Topmetal-I, for   ionizing radiation imaging
  Using industrial standard 0.35{\mu}m CMOS Integrated Circuit process, we realized a highly pixelated sensor that directly collects charge via metal nodes placed on the top of each pixel and forms two dimensional images of charge cloud distribution. The first version, Topmetal-I, features a 64x64 pixel array of 80{\mu}m pitch size. Direct charge calibration reveals an average capacitance of 210fF per pixel. The charge collection noise is near the thermal noise limit. With the readout, individual pixel channels exhibit a most probable equivalent noise charge of 330e-. 
Yan Fan, Chaosong Gao, Guangming Huang, Xiaoting Li, Yuan Mei, Hua   Pei, Quan Sun, Xiangming Sun, Dong Wang, Zhen Wang, Le ...
physics.ins-det hep-ex nucl-ex physics.med-ph