Amplification of the signal in triode structures of ion detectors based on 6H-SiC epitaxial films

Silicon carbide (SiC) is a wide band gap semiconductor with attractive properties for many applications. Recently, much progress has been made in preparing low-doped SiC films. The content of electrically active impurities in the films is controlled at the level of 10¹⁵ cm^-3 (for both n- and p-type) with lifetimes of several μs and -100 μs for holes and electrons, respectively. These characteristics, along with the radiation hardness of SiC, make it a candidate for use in detection and spectrometry of various kinds of nuclear radiation. In the present work, characteristics of an n-p-n⁺transistor structure have been studied. The conditions have been determined for substantial (tens of times) amplification of the nonequilibrium charge injected by an alpha particle into the structure. The structures were studied in a floating-base mode, with alpha particles produced by α ²⁴⁴Cm source coming from the Schottky barrier side. The alpha particles had energy of 5.8 MeV and range in SiC of 20 μm, exceeding the film thickness. Since the incidence angle of the particles was nearly 90°, the nonequilibrium charge appearing in the base corresponded (with account of the Bragg curve for ionization losses) to absorption of approximately one third of the above energy. The structures were connected in the circuit in series with a load resistance and a bias source. The signal from the alpha particles was recorded with a charge sensitive preamplifier. Further, the shape of the signal spectrum and the average amplitude as a function of applied voltage were determined using the conventional amplitude analysis technique