Improved barrier height of Schottky junctions formed on phosphidized AlInAs

Effect of surface phosphidization on the barrier height of n-AlInAs (Al 48%) Schottky diodes has been studied. The surface of AlInAs is treated with phosphine (PH₃) plasma at 250°C. X-ray photoelectron spectroscopy (XPS) analysis reveals that arsenic oxide on the conventionally etched surface is significantly reduced after phosphidization and that phosphorus atoms exist at and/or near the surface of AlInAs. Schottky junctions formed on the phosphidized AlInAs have metal-insulator-semiconductor (MIS) structure because oxides of phosphorus and aluminium are excellent insulators. The effective barrier height as high as 0.92 eV is successfully obtained for the Au/n-AlInAs Schottky junction with the true barrier height of 0.86 eV; this value is close to the ideal barrier height expected from Schottky-Mott model. As a result of the enhanced barrier height, the reverse leakage current can be reduced by more than five orders of magnitude in comparison with the case of conventional diodes. Marked dependence of the true Schottky barrier height on the metal work function is noted