【Device Papers】Vertical β-Ga₂O₃ Schottky diodes with LPCVD-grown Sn-doped drift layer

      Researchers from the University of Massachusetts Lowell have published a dissertation titled "Vertical β-Ga₂O₃ Schottky diodes with LPCVD-grown Sn-doped drift layer" in APL Electronic Devices.

Abstract

      High-quality Sn-doped (010) β-Ga₂O₃ homoepitaxial drift layers were grown by using the low-pressure chemical vapor deposition (LPCVD) method using solid elemental Sn as the n-type dopant source and integrated into vertical Ni/β-Ga₂O₃ Schottky barrier diodes to evaluate their device-level performance. β-Ga₂O₃ films with net carrier concentrations spanning from 2.0 × 10¹⁶ to 3.2 × 10¹⁷ cm⁻³ were achieved in thick epilayers exhibiting smooth surface morphology and high crystalline quality, as evidenced by surface rms roughness as low as 2.17 nm and an x-ray diffraction rocking-curve full width at half maximum as low as 38.9 arcsec. The fabricated diodes exhibited clear rectification and near-ideal thermionic-emission behavior, yielding ideality factors of 1.16–1.18 and Schottky barrier heights of 1.08–1.19 eV. The differential specific on-resistance (R_on,sp) decreased with increasing carrier concentration, with measured values ranging from 38.07 to 27.31 mΩ cm². Temperature-dependent current–voltage measurements ranging from 25 to 250 °C showed stable thermionic-emission-dominated transport, with a gradual reduction in Schottky barrier height and an increase in on-resistance due to phonon-limited mobility. Capacitance–voltage (C–V) analysis confirmed uniform and controllable doping profiles and yielded barrier heights between 1.12 and 1.29 eV, depending on carrier concentration. Temperature-dependent C–V measurements revealed a systematic reduction in built-in potential and barrier height with increasing temperature. Reverse-bias measurements demonstrated a breakdown voltage of 225 V for a diode with a drift-layer carrier concentration of 2.0 × 10¹⁶ cm⁻³ in the absence of any field-management structures, with two-dimensional Silvaco technology computer-aided design (TCAD) electrostatic simulations revealing peak electric fields localized at the Schottky anode edge, indicating edge-field-limited breakdown. These results demonstrate LPCVD as a viable approach for the growth of Sn-doped β-Ga₂O₃ drift layers that support high-quality Schottky interfaces with stable operation over a wide temperature range, providing a foundation for continued development of β-Ga₂O₃ high power devices.

DOI：

https://doi.org/10.1063/5.0319027