Journal of Applied Physics 109, 113711 (2011)

SCI

Electron scattering from polarization charges bound on a rough interface of polar heterostructures

Doan Nhat Quang, Nguyen Huyen Tung, and Nguyen Thanh Tien

We present the theory of an ad hoc scattering mechanism for carriers confined in a heterostructure (HS) made of polar materials, such as zinc blends, nitrides, and oxides. We show that the carriers in an actual polar HS must be laterally scattered extra from both piezoelectric and spontaneous polarization charges bound on a rough interface of the system. This is due to roughness-induced fluctuations in the position of interface polarization charges, so referred to as polarization roughness (PR) scattering. The new scattering is combined with the normal surface roughness (SR) scattering, giving rise to an effective roughness-related process, which is referred to as polarization surface roughness (PSR) scattering. The PSR scattering is found to be more important for nearly forward events and at small sheet carrier densities, and it is one of the key mechanisms governing transport in polar HSs. This enables a successful explanation of the mobility data on polar HSs made, e.g., of AlGaN/GaN, which has not been understood so far, starting only from the traditional scattering mechanisms