Ref HAL: hal-01208523_v1
DOI: 10.1063/1.4813220
WoS: WOS:000321761600027
Exporter : BibTex | endNote
Résumé:

We report magnetotransport measurements performed on AlGaN/GaN devices with different buffer layers. Standard samples with a 1 μm thick GaN buffer show a linear Hall resistance and an almost constant magnetoresistance, as expected from a single two-dimensional electron gas (2DEG) at the AlGaN/GaN interface. Other samples, with an Al x Ga1– x N buffer (x = 5%) and a buried linear aluminium gradient, have an additional three-dimensional electron slab (3DES) close to the GaN substrate. In this case, the Hall resistance is strongly non-linear and presents an incorrect hole-type carrier signature, evidenced by low field mobility spectrum analysis. This effect is strengthened when the 3D layer, parallel to the mesa-etched 2DEG, is infinite. We suggest that the misplacement of the electrical contacts in the 3DES, i.e., far from the sample edges, could explain the wrong carrier type determination.

Commentaires: The authors would like to thank Dr. E. Litwin-Staszewska from the Institute of High Pressure Physics “Unipress,” for the Hall bar processing on the 3D electron slab. This work was supported by the GANEX program (ANR-11-LabEx-0014).