Self-consistent quasi-two-dimensional model for computation of polarization-induced charge in nitride heterojunctions

Wide band gap nitride semiconductors, with potential use in optical devices in the blue region of the optical spectra and as high-power electrical devices, are gaining importance widely (Phys. Stat. Sol. (a) 187(1) (2001) 33; Phys. Stat. Sol. (a) 200 (2003) 118; Phys. Stat. Sol. (b) 228 (2001) 99; InT. J. Numer. Model.: Electron. Networks Dev. Fields 14 (2001) 303; J. Appl. Phys. 94 (2003) 3110; J. Appl. Phys. 94 (2003) 2779; Appl. Phys. Lett. 80 (2002) 3967; J. Appl. Phys. 87 (2000) 965). The carriers confined in the nitride heterojunctions owe their origin to the polarization field present in the structure as much as the dopants in the barrier (Rev. Mod. Phys. 54 (1982) 466; 56 (1997) R10024; Jpn. J. Appl. Phys. 41 (2002) 2531). Polarization being an important property of the nitride materials, affects the carrier confinement significantly. In this paper a quasi-two-dimensional model has been developed on the basis of a non sheet-like carrier distribution function and evaluating the quasi-Fermi level at the heterointerface. The model explains the carrier confinement studied experimentally in an AlGaN/GaN heterojunction (190 (2002) 65).