OBSERVATION OF QUANTUM HALL-EFFECT IN 2D-ELECTRON GAS CONFINED IN GANGAALN HETEROSTRUCTURE/

We report in this work magnetoresistance and Hall effect measurements performed on a GaN/GaAlN heterostructure in the 4.2 K-300 K temperatur e range. Well defined Hall plateaus are observed down to about 4 T, ty pical of the well-known quantum Hall effect. This confirms the 2D char acter of the electron gas at the GaN/GaAlN interface and gives evidenc e of the good quality of the sample. The bi-dimensionality of the stru cture has been additionally confirmed by the measurements under magnet ic field tilted with respect to the sample surface. However. the Hall density measured at low magnetic field is larger than that deduced fro m 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 i mportance is more and more pronounced when the temperature is increase d. (C) 1997 Elsevier Science S.A.