Enhanced Performance of Vertical <i>β</i>-Ga₂O₃ Schottky Barrier Diodes Through 212-MeV Low-Fluence Ge Ion Irradiation

The effects of 212-MeV Ge ion irradiation on the electrical performance of the vertical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga2O3 Schottky barrier diode (SBD) devices have been investigated in this work. With a fluence of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1} \times {10}^{{8}}$ </tex-math></inline-formula> ions/cm2, it is found that the electrical performance of the vertical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga2O3 SBD is significantly changed, including a decrease in the effective carrier concentration (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${N} _{\text {D}}$ </tex-math></inline-formula>) from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8.82\times 10^{{15}}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${2.64} \times {10}^{{15}}$ </tex-math></inline-formula> cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{3}}$ </tex-math></inline-formula>, a reduction in reverse current density (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${J} _{\text {R}}$ </tex-math></inline-formula>) from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.39\times 10^{-{6}}$ </tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.17\times 10^{-{7}}$ </tex-math></inline-formula> A/cm2, a restoration of the forward current density (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${J} _{\text {F}}$ </tex-math></inline-formula>) and series resistance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R} _{\text {S}}$ </tex-math></inline-formula>), and an increase in the reverse breakdown voltage (BV) from 218 to 420 V. Deep-level transient spectroscopy (DLTS) analysis reveals a decrease in the asymmetric defect peak at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E} _{\text {C}}-{0.78}$ </tex-math></inline-formula> eV in the virgin sample, accompanied by the appearance of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E} _{\text {C}} -0.84$ </tex-math></inline-formula> eV defect peak in the irradiated sample. This indicates that Ge ion irradiation can modify the arrangement of defect levels and interface states (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${N} _{\text {SS}}$ </tex-math></inline-formula>), consequently leading to reshaping the distribution of asymmetric defect peaks. Additionally, technology computer-aided design (TCAD) simulations demonstrate that the weakening of the metal-semiconductor (M-S) interface state, enhanced mobility, and the presence of deep-level defects in the bulk material together contribute to alter the electrical properties of the device postirradiation. Therefore, the low-fluence Ge ion irradiation can optimize the Au/Ni/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga2O3 interface and improve the electrical performance of the vertical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula>-Ga2O3 SBD.