Improved light reflectance and thermal stability of Ag-based ohmic contacts on p-type GaN with la additive

We investigated the effect of La additive on the improvement of light reflectance and thermal stability of Ag contacts on p-GaN. A high reflectance of over 90% at 460 nm wavelength and low specific contact resistivity of 5.5 × 10^-5 Ω cm² were obtained from La-containing Ag contacts annealed at 300 °C for 1 min, which also show better thermal stability than Ag contacts after annealing in air ambient. The experimental results reveal that the addition of La could effectively slow down Ag migration in 〈1 1 1〉 direction during annealing, and thus suppress the Ag agglomeration at elevated temperature, leading to a good ohmic contact with improved high reflectance and thermal stability.