HERA-B detectors with p-spray isolation on the n-side; unirradiated results

p-spray isolation of double-sided detectors is investigated by computer simulations and measurements on full-size detector prototypes. Simulations showed that a B p-spray implant doses 4/spl middot/10/sup 12/, 6/spl middot/10/sup 12/, and 8/spl middot/10/sup 12/ cm/sup -2/ and implant energy 60 keV would yield breakdown voltages above 200 V for unirradiated detectors with oxide charge 2/spl middot/10/sup 11/ cm/sup -2/. The simulations showed that the breakdown voltage decreases with increasing p-spray dose. According to the computer simulations, the detectors should perform equally well after irradiation giving an oxide charge of 1/spl middot/10/sup 12/ cm/sup -2/. HERA-B strip detectors with p-spray isolation were manufactured, using the three simulated doses. The average breakdown voltages and standard deviations were 167/spl plusmn/31 V for the 4/spl middot/10/sup 12/ cm/sup -2/ dose, 151/spl plusmn/16 V for the 6/spl middot/10/sup 12/ cm/sup -2/ dose, and 127/spl plusmn/13 V for the 8/spl middot/10/sup 12/ cm/sup -2/ dose. The measured decrease in breakdown voltage is in good agreement with the computer simulations.