Effect of rapid thermal annealing on deep level defects in the Si-doped GaN

Rapid thermal annealing effects on deep level defects in the n-type GaN layer grown by metalorganic chemical vapor deposition (MOCVD) have been characterized using deep level transient spectroscopy (DLTS) technique. The samples were first characterized by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The measurements showed that the barrier height of the as-grown sample to be 0.74 eV (I-V) and 0.95 eV (C-V) respectively. However, the Schottky barrier height of the sample annealed at 800 °C increased to 0.84 eV (I-V) and 0.99 eV (C-V) respectively in nitrogen atmosphere for 1 min. Further, it was observed that the Schottky barrier height slightly decreased after annealing at 900 °C. DLTS results showed that the two deep levels are identified in as-grown sample (E1 and E3), which have activation energies of 0.19 ± 0.01 eV and 0.80 ± 0.01 eV with capture cross-sections 2.06 × 10⁻¹⁷ cm² and 7.68 × 10⁻¹⁸ cm², which can be related to point defects. After annealing at 700 °C, the appearance of one new peak (E2) at activation energy of 0.49 ± 0.02 eV with capture-cross section σ_n = 5.43 × 10⁻¹⁷ cm², suggest that E2 level is most probably associated with the nitrogen antisites. Thermal annealing at 800 °C caused the E1 and E3 levels to be annealed out, which suggest that they are most probably associated with the point defects. After annealing at 900 °C the same (E1 and E3) deep levels are identified, which were identified in as-grown n-GaN layer.