Semiclassical theories of scattering mechanisms on 2DEG transport and the enhancement of electron mobility in Al(Ga)N/GaN heterostructures

Abstract Two-dimensional electron gases (2DEGs) play a central role in a wide range of electronic components. A thorough understanding of mobility-limiting scattering mechanisms is therefore crucial for the design of high-performance devices. In particular, with continuing device miniaturization, scattering processes such as interface roughness (IFR) scattering increasingly influence the mobility of more confined 2DEGs. This paper reviews the theoretical treatment of the essential scattering mechanisms within the effective mass theory, along with the solution of the Boltzmann transport equation via linearization and the momentum relaxation time approximation. An AlN/GaN high-electron-mobility transistor (HEMT) with experimentally measured mobility is used to evaluate multiple IFR scattering models and to examine the effect of static free-carrier screening on polar optical phonon (POP) scattering. Furthermore, to facilitate reproducibility, the inverse momentum relaxation time of each individual scattering mechanism is presented for a 2DEG density of 1×10 13 cm −2 . Finally, recent theoretical predictions of mobility enhancement in AlN/GaN HEMTs are highlighted.