Fundamental Role of Incomplete Dopant Ionization in Governing Electrostatics and Capacitance Response of n-β-Ga₂O₃/p-Si HeterojunctiONS
Abstract
Incomplete dopant ionization plays a decisive role in determining the electrostatic behavior and capacitance characteristics of n-type β-Ga₂O₃/p-type Si heterojunctions, particularly under cryogenic operating conditions. In this work, a comprehensive physics-based analytical framework incorporating temperature-dependent dopant activation, band alignment, carrier freeze-out, and mobility degradation is developed to investigate junction electrostatics over the 77–300 K range. The analysis reveals that incomplete ionization significantly modifies carrier distribution, depletion dynamics, and electric-field formation at low temperatures. For moderately doped structures (NA = ND = 4×10¹⁷ cm⁻³), freeze-out effects at 100 K reduce forward-bias capacitance by approximately 17%, increase depletion width by nearly 0.10 µm, and suppress the peak electric field by about 0.5 MV/cm. In contrast, heavily doped junctions (NA = ND = 1×10¹⁸ cm⁻³) exhibit comparatively weak temperature sensitivity, with electrostatic variations below 5% due to enhanced dopant activation stability. Temperature-dependent Cp–n(V) characteristics demonstrate gradual convergence toward full-ionization behavior above 250–300 K, confirming the transition from partial to near-complete dopant activation. Furthermore, the junction capacitance follows a hyperbolic voltage dependence (C ∝ 1/√ΔV), with strong capacitance compression observed under extreme forward bias. The presented results establish a quantitative understanding of freeze-out-controlled electrostatics in Si/β-Ga₂O₃ heterostructures and provide a predictive foundation for the optimization of cryogenic, high-frequency, and high-voltage ultra-wide-bandgap semiconductor devices.
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Copyright (c) 2026 D.A. Qalandarova, D.A. Saparbayeva, A.A. Medatov, G.T. Zaripov, M. Ziyayeva, S. Temirov, K.R. Sattarkulov, Sh. Saidova
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