Thermoresistive and piezoresistive properties of wurtzite n-GaN

We performed thermo and piezoresistive measurements on GaN bulk samples grown with different techniques (PIMBE, MOCVD). By analysing the I(V) characteristics as a function of temperature, we found a temperature coefficient of resistance (TCR ¼ a) of the same order of magnitude (a few percent per C) as commercial thermistors, with a peak value of 19%/C. The measured gauge factor is about five, a value comparable with that obtained for GaN by other groups. We also performed PC vs. temperature measurements on a MQW GaN/AlGaN finding a peak shift of about 0.4 meV/K.