Observation of quantum Hall effect in 2D-electron gas confined in GaN/GaAlN heterostructure

We report in this work magnetoresistance and Hall effect measurements performed on a GaN/GaAlN heterostructure in the 4.2 K-300 K temperature range. Well defined Hall plateaus are observed down to about 4 T, typical of the well-known quantum Hall effect. This confirms the 2D character of the electron gas at the GaN/GaAlN interface and gives evidence of the good quality of the sample. The bi-dimensionality of the structure has been additionally confirmed by the measurements under magnetic field tilted with respect to the sample surface. However, the Hall density measured at low magnetic field is larger than that deduced from Shubnikov De Haas measurements. This clearly indicates the existence of a parallel conduction through the GaAlN layer. The analysis of the temperature dependence of the transport coefficients shows that its importance is more and more pronounced when the temperature is increased.