Figure 1. I –VT curves for n-type Al-GaN for different temperatures. The slope of these lines increases with temperature T and is directly proportional to the electrical conductivity σΩ1cm-1).

From

Electric Properties of n-GaN: Effect of Different Contacts on the Electronic Conduction

S. Abdalla, F. Marzouki, S. Al-ameer, S. Turkestani

International Journal of Physics. 2013, 1(2), 41-48 doi:10.12691/ijp-1-2-3