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

Abstract

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 0.74eV (I-V) and 0.95eV (C-V) respectively. However, the Schottky barrier height of the sample annealed at 800^oC increased to 0.84eV (I-V) and 0.99eV (C-V) respectively in nitrogen atmosphere for 1min. Further, it was observed that the Schottky barrier height slightly decreased after annealing at 900^oC. DLTS results showed that the two deep levels are identified in as-grown sample (E1 and E3), which have activation energies of 0.19+/-0.01eV and 0.80+/-0.01eV with capture cross-sections 2.06x10^-^1^7cm^2 and 7.68x10^-^1^8cm^2, which can be related to point defects. After annealing at 700^oC, the appearance of one new peak (E2) at activation energy of 0.49+/-0.02eV with capture-cross section @sn=5.43x10^-^1^7cm^2, suggest that E2 level is most probably associated with the nitrogen antisites. Thermal annealing at 800^oC 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^oC the same (E1 and E3) deep levels are identified, which were identified in as-grown n-GaN layer.