Observation of Negative Magnetoresistance in Gallium Nitride HEMT Structures

Negative Magnetoresistance (NMR) was observed in GaN HEMT structures grown by MOCVD and was studied in the temperature range of 1.9–77 K and under magnetic field from 0—8T. The presence of NMR is directly related to disorder in the structures and is likely due to the simultaneous presence of short-range (strong) scattering centres due to interface roughness and/or alloy disorder and smooth disorder(random potential due to remote impurities). Moreover the low values of quantum scattering time glean an insight to the presence of interface roughness in all the samples. The degree of disorder can be ascertained qualitatively through values of NMR in conjecture with quantum scattering time, mobility and carrier concentrations values.