Si-detectors with internal proportional charge amplification

The results of investigation of special strip and pixel detectors are presented. The possibility to achieve the internal amplification mode similar to proportional gas counters in a pixel detector made from n-type silicon is shown. An "amplified" peak at the energy 70 MeV with the energy resolution FWHM similar to 10 MeV is visible on the alpha-spectrum of Pu-238 (E-alpha = 5.5 MeV). The real internal amplification effect (with a gain of 20) has been demonstrated with the detectors made from p-silicon. In this case, the detector could be used as a spectrometric device even in the amplification mode. The most important result of our investigation is the feasibility of efficient decrease of energy registration threshold for ionizing radiation in Si devices at room temperature. This effect has been achieved in the measurement with a Fe-55 source (E-gamma = 5.9 keV).