Highly tunable, polarization-engineered two-dimensional electron gas in ε-AlGaO₃/ε-Ga₂O₃ heterostructures

P. Ranga,  S. B. Cho, R. Mishra, S. Krishnamoorthy, Appl. Phys. Express 13 061009 (2020).

We report on the modeling of polarization-induced two-dimensional electron gas (2DEG) formation at ε-AlGaO₃/ε-Ga₂O₃ heterointerface and the effect of spontaneous polarization (P _sp) reversal on 2DEG density in ε-Ga₂O₃/ε-AlGaO₃/ε-Ga₂O₃ double heterostructures. Density-functional theory (DFT) is utilized to calculate the material properties of ε-Ga₂O₃ and ε-AlGaO₃ alloys. Using Schrödinger–Poisson solver along with DFT calculated parameters, the 2DEG density is calculated as a function of barrier type and thickness. By optimizing the layer thicknesses of ε-Ga₂O₃/ε-AlGaO₃/ε-Ga₂O₃ heterostructures, charge contrast ratios exceeding 1600 are obtained. This computational study indicates the high potential for ε-Ga₂O₃-based heterostructure devices for non-volatile memories and neuromorphic applications.