Preliminary characterisation of CdTe M-π-n diode structures

Due to the high Z, 1 mm CdTe (Z=52, 48) offers a high absorption probability for photons with energies up to 100 keV (Zwerger and Fiederle, 2007). In order to further reduce the dark current flowing through the sensor when applying high voltage, CdTe diode structures (M-π-n) have been processed at the Freiburg Materials Research Center (FMF). As comparison, CdTe sensors with ohmic contacts, working as photoresistors have also been produced. The different sensor structures have been flip-chip bonded on Medipix2 readout electronics (Llopart and Campbell, 2002). This work reports on the I-V characteristics of the different sensor structures, confirming the improved leakage current flowing through the diode structure. Furthermore, the imaging capabilities of the diode structures with respect to their spatial resolution are presented.