Electron scattering analysis in 2DEG in sputtering-grown MgZnO/ZnO heterostructure

Abstract

Here, we present an analytical modeling of electron mobility in two dimensional electron gas (2DEG)-yielding MgZnO/ZnO heterostructures, to ascertain dominant scattering mechanisms and physical parameters responsible for one-order lower value of electron mobility in sputtering-grown heterostructure as compared to that in molecular beam epitaxy-grown heterostructure. This work extensively probes all scattering components and their physical parameters, such as dislocation density, impurity density, mole fraction, 2DEG density, correlation length and lateral size, for their respective effects on electron mobility of sputtered heterostructure. The results suggest that dislocation density and alloy disorder scattering are the most dominant sources responsible for reduced electron mobility. This work is extremely crucial for achieving high electron mobility by optimizing the material growth parameters to attain low dislocation density, impurity density and interface roughness, for the development of low-cost ZnO-based heterostructure field effect transistors.

Analytical Study of ZnO-based HEMT for Power Switching

“…Higher values of P D in MZO HEMT are mainly due to the lower 2DEG mobility, which leads to the high values of R sh and R ON . In addition to this, large dislocation and alloy disorder scattering also influence the rise in R sh in DIBS grown MZO-based HEMT [25,26]. The values of P DD at minimum D are 942 W/cm 2 for AlGaN/GaN HEMT and 1044 and 1062 W/cm 2 for MZO HEMTs by MBE and DIBS, respectively.…”

Rapid Thermal Annealing for Surface Optimisation of ZnO Substrates for MBE-Grown Oxide Two-Dimensional Electron Gases

“…High mobility 2DEGs require a low density of scattering centres. These can be formed by crystalline defects [8], ionized donors [9], alloy scattering [8], electron-electron scattering [10] or atomic impurities [11]. Minimizing the crystalline defect density requires the use of an epitaxially matched substrate, with the best results found using single-crystal ZnO [2].…”

“…There is a trade-off to be made between electron density and electron-induced scattering which is determined by the Mg concentration of ZnMgO layers [13,14]. In MBE-grown ZnO/ZnMgO 2DEGs, interface roughness scattering and impurity scattering have been shown to be the dominant factors for electron mobility [8]. It is known, for instance, that lithium acts as an acceptor in ZnO and can significantly reduce ZnO conductivity [15][16][17] and harm 2DEG formation [11].…”

Rapid Thermal Annealing for Surface Optimisation of ZnO Substrates for MBE-Grown Oxide Two-Dimensional Electron Gases

“…High mobility 2DEGs require a low density of scattering centres. These can be formed by crystalline defects [7], ionized donors [8], alloy scattering [7], electron-electron scattering [9] or atomic impurities [10]. Minimizing the crystalline defect density requires the use of an epitaxially matched substrate, with the best results found using singlecrystal single crystal ZnO [1].…”

“…There is a trade-off to be made between electron density and electron-induced scattering which is determined by the Mg concentration of ZnMgO layers [12,13]. In MBE-grown ZnO/ZnMgO 2DEGs, interface roughness scattering and impurity scattering have been shown to be the dominant factors for electron mobility [7]. It is known, for instance, that lithium acts as an acceptor in ZnO and can significantly reduce ZnO conductivity [14][15][16] and harm 2DEG formation [10].…”