【Member Papers】Professor Fang Zhilai of Fudan University: All Gallium Oxide films homogeneous p-n junction

      The preparation of p-n junction and the exploration of its physical mechanism play a key role in developing various functional devices and promoting its practical application. ultra-wide band gap semiconductors have great application potential in the preparation of high voltage and high frequency devices, but the difficulty of Gallium Oxide P-type doping limits the preparation of Gallium Oxide homogeneous p-n junction and hinders the development of all Gallium Oxide based bipolar devices.

      Recently, Professor Fang Zhilai of Fudan University and others published a research paper in Science China Materials, through an advanced phase transition growth technology combined with sputtering coating method, successfully prepared N-type tin doped β phase Gallium Oxide/P-type nitrogen doped β phase Gallium Oxide thin films.

Key points of this article

1) All Gallium Oxide single-side mutation homogenous p-n junction diodes were successfully fabricated, and the device mechanism was analyzed in detail.

2) The diode achieved a rectification ratio of 4 × 10⁴, a low on-resistance of 9.18 mΩ cm² at 40 V, a built-in potential of 4.41 V and an ideal factor of 1.78 and showed no overshoot rectification characteristics and long-term stability under AC voltage.

      This work provides a preliminary glimpse into the gateway of Gallium Oxide homogeneous p-n junction, lays a foundation for Gallium Oxide homogeneous bipolar devices, and opens a path for the application of high voltage and high power devices.

Figure 1.(a) HRTEM images of Sample SP obtained at different locations of the β-Ga₂O₃/GaN interface. (b) Formation energy versus chemical potential of O atoms ΔμO. (c) Transition level of the NO(III)acceptor.

Figure 2.(a) Hall voltage versus magnetic field curve from van der Pauw Hall effect measurement of the N-doped β-Ga₂O₃ thin films. (b) Drain-source current (IDS) versus gate-source voltage (VGS) characteristic curve of the N-doped β-Ga₂O₃ films top-gate FET in linear and log scale at a drain-source voltage (VDS) of 20 V. (c) XRD spectrum of the Sn-doped β-Ga₂O₃/N-doped β-Ga₂O₃ films on the sapphire substrate. (d) SIMS depth profile of the Sn-doped β-Ga₂O₃/N-doped β-Ga₂O₃ films showing the concentrations of Sn and N. (e) SIMS elemental mappings of Ga (brown), O (red), Al (green), Sn (pink), N (blue) components, and the layer structure of the β-Ga₂O₃ film. (f) Hall voltage versus magnetic field curve from van der Pauw Hall effect measurement of the Sn-doped β-Ga₂O₃ thin films. (g) IDSversus VGScharacteristic curve of the Sn-doped β-Ga₂O₃ back-gate FET in linear and log scale at a VGSof 20 V.

Figure 3.(a) Schematic of the n-type Sn-doped β-Ga₂O₃/p-type N-doped β-Ga₂O₃ homojunction diode (Vpn). (b) I - V and (c) C–V curves with the applied voltage Vnnon Pad 1/2 and the applied voltage Vppon Pad 3/4. (d) Forward current density and Ron,spversus applied voltage curve. (e) Current density versus voltage curves of the beta -Ga₂O₃ p-n homojunction diode measured on the first month and the seventh month. (f) Rectified output current using the beta-Ga₂O₃ diode by applying an AC. Measured on the first month and the seventh month. (f) Rectified output current using the beta-Ga2O3diode by applying an AC  square wave.

Figure 4.Schematic band diagrams of (a) p-type and n-type β-Ga₂O₃, and (b) Schematic band diagrams and internal mechanisms of β-Ga₂O₃ p-n homojunction. (c) Schematic band diagrams and internal mechanisms of β-Ga₂O₃ p-n homojunction under different biases.

The original link: https://doi.org/10.1007/s40843-023-2741-4