Conduction mechanisms on annealed semi-insulating GaAs samples

We have measured electrical resistivity in the range of 100-500 K on six semi-insulating low-temperature grown molecular-beam epitaxy GaAs samples that were exposed to annealing treatment. Samples 2, 3, 4, 5 and 6 were annealed with temperatures of 350 degrees C, 400. C, 450 degrees C, 500 degrees C and 550 degrees C, while sample 1 was not exposed to the annealing process. We used the differential activation energy method to precisely identify the temperature region where the different conduction regimes dominate, i. e. band conduction, nearest neighbor hopping and variable range hopping. We will also show that the change on the density of states in the impurity band caused by annealing significantly alters the conduction mechanisms present in those samples.