Tensoelectrical Properties of Electron-Irradiated N-Si Single Crystals

Abstract

Tensoresistance at uniaxial pressure for electron-irradiated n-Si single crystals at room temperature has been studied. Silicon single crystals for research were doped with phosphorus, concentration N_d=2.2·10¹⁶ cm^-3, and irradiated by the electron flows of 5·10¹⁶ el./cm², 1·10¹⁷ el./cm² and 2·10¹⁷ el./cm² with the energy of 12 MeV. Measurements of tensoresistance and Hall constant were performed for the uniaxially deformed n-Si single crystals along the crystallographic directions [100] and [111]. Mechanisms of tensoresistance for the investigated n-Si single crystals were established based on the measurements of the tenso-Hall effect and infrared Fourier spectroscopy. It is shown that the tensoresistance of such single crystals is determined only by changes in the electron mobility under the deformation. In this case, the electron concentration will not change under the action of uniaxial pressure, because the deep levels of radiation defects belonging to the VO_i VO_iP complexes will be completely ionized. Ionization of the deep level of E_V+0.35 eV, which belongs to the defect of C_iO_i, under the deformation will not be manifested and will not be affect on the tensoresistance of n-Si. It is established that the anisotropy of electron scattering on the created radiation defects, which occurs at the uniaxial pressure along the crystallographic direction [100], is the cause of different values of the magnitude of tensoresistance of n‑Si single crystals, irradiated by different electron flows. For the case of tensoresistance of the uniaxially deformed n-Si single crystals along the crystallographic direction [111], the dependence of its magnitude on the electron irradiation flow is associated with changes in the screening radius due to an increase in the effective electron mass. For the first time obtained at room temperature the increase of the magnitude of tensoresistance for the n-Si single crystals due to their irradiation by the electron flows of Ω ≥1·10¹⁷ el./cm² can be used in designing high uniaxial pressure sensors based on such n-Si single crystals with the higher value of tensosensitivity coefficient regarding available analogues. Such sensors will have increased radiation resistance and a wide scope of operation.