p+/n-/n+ cz-Si detectors processed on p-type boron-doped substrates with thermal donor induced space charge sign inversion

We have processed pad detectors on high-resistivity p-type Cz-Si wafers. The resistivity of the boron-doped silicon is approximately 1.8 kΩ cm after the crystal growth. The detector processing was carried out using the common procedure for standard n-type wafers, to produce p⁺/p/p^-/n⁺ detector structures. During the last process step, i.e., sintering of aluminum electrode, the p-type bulk was turned to n-type through generation of thermal donors (TD). This way, high oxygen concentration p⁺/n^-/n⁺ Cz-Si detectors were realized with low temperature process. The full depletion voltage of detectors could be tailored between wide range from 30 V up to close 1000 V by changing heat treatment at 400°C-450°C duration from 20 to 80 min. The space charge sign inversion (SCSI) in the TD generated devices (from p⁺/p^-/n⁺ to p⁺/n^-(inverted)/n⁺) has been verified by transient current technique measurements. The detectors show very small increase of full depletion voltage after irradiations with 24 GeV/c protons up to 5*10¹⁴ p/cm².