We study the electron transport within bulk wurtzite ZnO and its nþ–n–nþ diode by the Ensemble Monte Carlo method. In bulk ZnO we study the steady state and transient situation with three valley model for the conduction band and compare the results with GaN. Our results show that ZnO’s threshold field occurs at a higher applied electric field than GaN. Also, velocity overshoot in ZnO occurs at higher electric fields, too. But the overshoot relaxation time is about 0.3 ps for both of them. As the results show, the role of the third valley is tiny, so for a diode we use two valley conduction bands. For anode voltage ranges from 0.25 to 3 V, we simulate the profiles of the electron density, electric field, potential, average electron velocity, and compare the results with that for GaN. Our results show, as we expect, electron velocity in active layer in the GaN diode is faster than in ZnO.

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