Enhancement of device performance in β-Ga₂O₃ Schottky barrier diodes with tetramethylammonium hydroxide treatment

Schottky barrier diodes were fabricated on tetramethylammonium hydroxide (TMAH)-treated β-Ga₂O₃ surfaces with Ni/Au as Schottky metal contacts. TMAH wet surface treatment efficiently reduced the roughness of the β-Ga₂O₃ surface. An X-ray photoelectron emission analysis of the TMAH-treated β-Ga₂O₃ surface chemical binding features indicates the effective removal of unwanted surface oxides and contaminants formed unintentionally by chemisorption during exposure to ambient conditions. The TMAH-treated Au/Ni/β-Ga₂O₃ Schottky diode displayed improved rectification behavior with an increment of barrier height by 0.30 eV compared to the untreated diode. The breakdown voltages (V_br) for the untreated and TMAH-treated Au/Ni/β-Ga₂O₃ Schottky barrier diode are 298 and 358 V, respectively. The decrease in the turn-on resistance (R_on) in the Au/Ni/β-Ga₂O₃ Schottky barrier diode by TMAH treatment can be ascribed to the improved surface morphology. The improved electrical behavior of the Au/Ni/β-Ga₂O₃ Schottky barrier diode formed on the TMAH-treated β-Ga₂O₃ surface can be accredited to the oxygen vacancies reduction, that deceased the carrier concentration in the β-Ga₂O₃ epilayer and to the improved the surface morphology. These results demonstrate the effectiveness of TMAH wet surface treatment on β-Ga₂O₃ and its potential as a simple method for fabricating β-Ga₂O₃-based devices with improved performance.