We report electrical and optical measurements performed on low-doped, n-type 4H-SiC. We show that below a typical carrier concentration of similar to5 10(15) cm(-3) at room temperature, they work in the so-called exhaustion regime from 300 K. The carrier concentration remains constant and the resistivity increases linearly at a rate of 3400 ppm/K from 500 to 800 K. This establishes low doped SiC as a good candidate to produce high performance Hall sensors, working in harsh environment, with a large sensitivity and a low thermal drift.