Electron mobility modulated by optical phonons in AlxGa1-xN/InyGa1-yN/GaN/AlN heterostructures. (March 2021)

• Record Type: Journal Article
• Authors: Chai, Y.J.; Zan, Y.H.; Ban, S.L.
• Is Part Of: Superlattices and microstructures. Volume 151(2021)
• Publication Date: 2021-03
• Subjects: Electron mobility -- Asymmetric heterostructures -- Composite channel -- Ternary mixed crystal -- AlGaN/GaN; Superlattices as materials -- Periodicals; Microstructure -- Periodicals; Semiconductors -- Periodicals; Superréseaux -- Périodiques; Microstructure (Physique) -- Périodiques; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.spmi.2021.106821
• Languages: English
• ISSNs: 0749-6036

Abstract

Abstract: The electron mobility influenced by optical phonons, the size of InGaN/GaN channels and In composition y in wurtzite Al x Ga1- x N/In y Ga1- y N/GaN/AlN heterostructures as basic structures of high electron mobility transistors (HEMTs) is investigated around room temperature. The electron states affected by the two-dimensional electron gas near the interfaces are obtained by self-consistently solving the Poisson and Schrödinger equations. Based on the dielectric continuum and Loudon's uniaxial crystal models combined with the transfer matrix methods, the dispersion relations and electrostatic potentials of interface (IF), confined (CO), half space, and propagating optical phonons are discussed in detail, as well as the corresponding transformations among different phonon modes. Furthermore, the mobility contributed by optical phonons is given by the Lei and Ting's force balance and energy balance equations. Our results show that the electron mobility in the heterostructures with composite InGaN/GaN channel is mainly dominated by IF and CO phonon modes, and is higher than that in the conventional heterostructures with GaN-channels. Meanwhile, the optimized size and In composition of the composite channel to improve the mobility are also clarified. Highlights: Electron mobility affected by optical phonons, optimized size and In composition in wurtzite asymmetric AlGaN/InGaN/GaN/AlGaN heterostructures. The electron states affected by the two-dimensional electron gas near the interfaces are obtained. The dispersion relations and electrostatic potentials of optical phonons and the corresponding transformations among different phonon modes are discussed. For most structures we calculated, the CO phonon modes with higher frequencies play a dominate role to determine the electron mobility but the IF modes are non-negligible for especially for less In composition.