Special features of alpha-particle detection with thin semi-insulating 6H-SiC films

The p(+)-n-n(+) structures based on 6H-SiC films grown by chemical vapor de position on the n(+) substrate were irradiated with 8-MeV protons with a do se of 8 x 10(15) cm(-2). In order to stabilize the material, it was anneale d for 10 min at 450 degreesC. As a result, the resistivity of the film was rho = 5 x 10(9) Omega cm. The effect of proton irradiation was studied by a lpha spectrometry. The 5.77-MeV alpha particles were detected for both reve rse and forward bias voltages applied to the structure. The results of the following two modes of detection were compared: (i) a particle traverses th e structure without losing much of its energy, and (ii) a particle is stopp ed in the structure. It is shown that, in the former case and under a forwa rd bias, a signal is formed by a mechanism involving a "through-conducting channel." This makes it possible to determine the product of lifetime of el ectrons by their mobility. The situation in which the particle range R does not exceed the film thickness was analyzed; this situation is typical of s pectrometry. It is noted that a decrease in R results in different behavior of the signal for the bias voltages of opposite polarity. Thus, for forwar d bias, the signal amplitude decreases more rapidly and for larger values o f R. (C) 2000 MAIK "Nauka/Interperiodica".