Design and simulation of betavoltaic angle sensor Based on 63Ni–Si

• The angle sensor based on 63Ni–Si in small dimensions for operating in the wide range of temperature and full-angle measurement was proposed.
• The rate of electron–hole pair generation in silicon was obtained using Monte Carlo MCNP4C code.
• Effects of temperature and activity on the accuracy of the measurement of angle were investigated.
• Temperature calibration was considered simultaneously in the proposed structure (self-correcting).

A theoretical design and simulation of betavoltaic angle sensor (beta-AS) based on 63Ni–Si using MCNP code is presented in this article. It can measure the full angle of 0–360° in the temperature range of 233–353 K. Beta-AS is composed of semicircular 63Ni as the beta source, which rotates along the circular (four-quadrant) surface of Si as a semiconductor (in p–n structure), so that the change in the source angle in relation to Si surface can be measured based on the changes in Voc observed in each quadrant of Si. For better performance, characteristics of Si and 63Ni have been optimized: ND and NA values of 8e19 and 4e18 cm−3 (donor and acceptor doping concentration in Si, respectively), source thickness and activity of 1.5 µm and 18 mCi, respectively. The relation between angle and Voc is also investigated. The maximum difference between measured and real values of angle (the worst case, i.e., 0.18° for the angle of 45°) occurs at 233 K. It has been shown that sensitivity of the sensor decreases with an increase of angle. The results also show that the change in activity does not affect the sensitivity.