Effect of KOH treatment on the Schottky barrier height and reverse leakage current in Pt/n-GaN

The effect of potassium hydroxide (KOH) treatment was investigated for Pt/n-GaN Schottky diodes using current-voltage (I-V) and capacitance-voltage (C-V) characteristics. Atomic force microscopy (AFM) showed that the surface profile did not change significantly as a result of KOH treatment. The Schottky barrier height increased for both I-V and C-V measurements. The reverse leakage current was also reduced by KOH treatment. By fitting these data to the reverse current based on the thermionic field emission (TFE) model, it was shown that the experimental results are consistent with the presence of high densities of surface states, which were reduced appreciably by KOH treatment. The similar behavior of Pt/n-GaN samples grown by hydride vapor phase epitaxy (HVPE) suggests that the KOH treatment is effective in improving the rectifying characteristics of Schottky barriers to n-GaN grown by both organometallic vapor phase epitaxy (OMVPE) and HVPE.