THE HOMOGENEITY OF THE PHOTONUCLEAR TRANSMUTATION DOPING OF SILICON

The results of measurements of the electrical properties of silicon do ped with aluminium by the photonuclear transmutation doping (PTD) tech nique are presented. The main consideration is a study of the homogene ity of the distribution of resistivity in the volume of p-type and n-t ype PTD silicon single crystals. The inhomogeneity of the resistivity is found to be a function of the inhomogeneity of the irradiation fiel d and of the initial crystal doping level. Thus, by choosing the requi red uniformity of the irradiation field and by selecting the appropria te starting material, variations of the distribution of resistivity of p-type PTD Silicon, both on a macroscopic and on a microscopic scale, can be reduced to a few per cent. The production of p-type and n-type high-resistivity silicon for detector fabrication is considered as a feasible commercial application of the PTD technique. The initial crys tals of silicon were irradiated by bremsstrahlung beams with endpoint energies in the range of 30 to 35 MeV on the Kurchatov Institute elect ron linear accelerator FAKEL using a prototype irradiation facility de signed to provide a uniform bremsstrahlung fluence over the volume of a silicon target.