Abstract

"The junction termination extension (JTE) avalanche photodiode (APD) with a ring structure around the active area was built with the use of planar technology processing of float zone silicon doped by neutron transmutation. The main junction and JTE structure have been processed simultaneously, by one implantation step followed by annealing. To set a difference in the doping levels of silicon in the main junction and in the ring structure, the single oxide mask was developed with openings gradually patterned on planar surface. To provide a contact with low resistivity the surface of the main junction was covered by a thin silicon p+-layer, grown with MBE (molecular beam epitaxy). The thickness of this ""dead"" layer no more than 100 nm was obtained. As have been found, the dark current is strongly dependent on the implanted dose, decreasing with decreasing dose from 5×1012 to 2×1012 cm-2. The detectors built with the lowest dose only have the level of dark currents suitable for the measurement of the gain resulted from carrier multiplication. The gain up to 25 was obtained for visible light (?=600 nm) and up to 7×103 for single 2.5 MeV a-particles. For 4.3 MeV ?particles the best energy resolution of 330 keV FWHM was obtained. For 22.16 keV x-ray from a 109Cd source the resolution of 4.7 keV FWHM have been measured, which corresponds to 560 rms electrons noise."