Epitaxial growth of Cr₂MnO₄/β-Ga₂O₃p-n heterojunctions for power electronics

Gallium oxide (β-Ga₂O₃) has emerged as a promising material for next-generation high-power electronic devices due to its ultra-wide bandgap and high Baliga’s figure of merit. However, while n-type β-Ga₂O₃ is readily attainable, achieving stable p-type conductivity remains a significant challenge, limiting its application to unipolar (n-type only) devices. Identifying a compatible p-type semiconductor is therefore essential for realizing Ga₂O₃-based bipolar devices. In this work, we demonstrate the heteroepitaxial growth of p-type Cr₂MnO₄ thin films on n-type β-Ga₂O₃ (01) substrates using off-axis sputter beam epitaxy. Structural characterization by X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) confirmed high crystalline quality and epitaxial alignment. The fabricated Cr₂MnO₄/β-Ga₂O₃ heterojunctions exhibited strong rectifying behavior with on/off current ratios up to 10⁸. Capacitance–voltage measurements revealed intrinsic p-type conductivity with carrier concentrations on the order of 10¹⁷ cm^-3. The growth optimization, microstructural analysis, and electrical characteristics of these p–n heterojunctions will be discussed.