Deep UV detection by CVD diamond position sensitive devices

The photoresponse of different photoconductive diamond sensors to excimer laser pulses is investigated as a function of the pulse energy E over three order of magnitude. The integrated photoresponse pulse intensity changes according to the power law I Eβ. Initially, the pulse intensity increases linearly with the pulse energy up to a turning point, which depends on the electronic quality of the diamond film, where a sublinear behavior (β=0.5) is found. The photoresponse pulse shape also changes accordingly, largely broadening at high pulse energies. Such behavior has been interpreted in terms of monomolecular and bimolecular recombination mechanisms acting in different pulse intensity ranges. A further reduction of β is also observed at very high intensity in less defected samples, where the induced carrier density is high enough to cause carrier–carrier scattering and mobility reduction.