ELECTRICAL AND TENSOELECTRICAL PROPERTIES OF THE γ-IRRADIATED n-Si SINGLE CRYSTALS

Abstract

The electrical properties and tensoresistive effect at the uniaxial pressure along the crystallographic direction [100] for unirradiated and γ-irradiated silicon single crystals, doped by the phosphorus impurity were investigated at the liquid nitrogen and room temperature. Based on measurements of the Hall effect, it was established that increasing the dose of γ-irradiation is decreasing the concentration and mobility of electrons in n-Si single crystals. A significant decrease of the electron concentration at T=77 K for irradiated n-Si single crystals by the dose of Ω=5·10⁸ R is associated with the formation at γ-irradiation of a significant concentration of the acceptor levels of radiation defects (A- and E-centres, divacancies and others). For doses of γ-irradiation Ω<5·10⁷ R, the presence of the tensoresistive effect of n-Si is explained by the decrease in the electron mobility under the uniaxial pressure since the electron concentration practically remains constant. The decrease in resistivity at the transition through the maximum dependence for the γ-irradiated n-Si single crystals by the dose of Ω=5·10⁸ R is associated with the increasing electron concentration due to ionization of the local levels of radiation defects with increasing the uniaxial pressure. Experimental measurements of the Hall effect and tensoresistive effect correlate well with the obtained dependences of the tensosensitivity coefficient. From the analysis of these dependencies, it follows that an increase in temperature and dose of γ -radiation leads to a decrease in the tensosensitivity coefficient of n-Si. The obtained results can find their practical application for the design of radiation-resistant pressure sensors based on n-Si single crystals.