Non-monotonic magnetoresistance in an AlGaN/GaN high-electron-mobility transistor structure in the ballistic region

• Published in: Journal of the Korean Physical Society 2014, 64(10), , pp.1572-1576
• Main Authors: Wang, Yi-Ting, Woo, Tak-Pong, Lo, S.-T., Kim, Gil-Ho, Liang, Chi-Te
• Format: Article
• Language: English
• Subjects: Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Theoretical; 물리학
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.64.1572

In this report, we will discuss the nonmonotonic magnetoresistance (MR) in an AlGaN/GaN high-electron-mobility transistor (HEMT) in a perpendicular magnetic field B in the ballistic region ( kBTτ/ħ < 1) and in the weakly-disordered limit ( kFl = 159 ≫ 1), where kB, T , τ, ħ , k F , and l represent the Boltzmann constant, temperature, elastic scattering time, reduced Planck constant, Fermi wave vector and mean free path, respectively. The MR shows a local maximum between the weak localization (WL) and the Shubnikov-de Haas regions. In the low magnetic field regime, the quantum correction to the conductivity is proportional to T −3/2 , which is consistent with a recent theory [T. A. Sedrakyan, and M. E. Raikh, Phys. Rev. Lett. 100, 106806 (2008)]. According to our results, as the temperature is increased, the position of the MR maximum in B increases. These results cannot be explained by present theories. Moreover, in the high-magnetic-field regime, neither the magnetic and nor the temperature dependences of the observed MR is consistent with present theories. We, therefore, suggest that while some features of the observed nonmonotonic MR can be successfully explained, further experimental and theoretical studies are necessary to obtain a thorough understanding of the MR effects.