Characterization of Al/Si junctions on Si(100) wafers with chemical vapor deposition-based sulfur passivation

Chemical vapor deposition-based sulfur passivation using hydrogen sulfide is carried out on both n-type and p-type Si(100) wafers. Al contacts are fabricated on sulfur-passivated Si(100) wafers and the resultant Schottky barriers are characterized with current-voltage (I-V), capacitance-voltage (C-V) and activation-energy methods. Al/S-passivated n-type Si(100) junctions exhibit ohmic behavior with a barrier height of <0.078 eV by the I-V method and significantly lower than 0.08 eV by the activation-energy method. For Al/S-passivated p-type Si(100) junctions, the barrier height is ∼0.77 eV by I-V and activation-energy methods and 1.14 eV by the C-V method. The discrepancy between C-V and other methods is explained by image force-induced barrier lowering and edge-leakage current. The I-V behavior of an Al/S-passivated p-type Si(100) junction remains largely unchanged after 300 °C annealing in air. It is also discovered that heating the S-passivated Si(100) wafer before Al deposition significantly improves the thermal stability of an Al/S-passivated n-type Si(100) junction to 500 °C.