Deep Levels in n-Type Schottky and p⁺-n Homojunction GaN Diodes

Abstract

The deep level spectra in both p⁺-n homojunction and n-type Schottky GaN diodes are studied by deep level transient spectroscopy (DLTS) in order to compare the role of the junction configuration on the defects found within the n-GaN layer. Both majority and minority carrier DLTS measurements are performed on the diodes allowing the observation of both electron and hole traps in n-GaN. An electron level atE_c-E_t=0.58 and 0.62 V is observed in the p⁺-n and Schottky diodes, respectively, with a concentration of ∼3-4×10¹⁴cm⁻³ and a capture cross section of ∼1-5×10⁻¹⁵cm². The similar Arrhenius behavior indicates that both emissions are related to the same defect. The shift in activation energy is correlated to the electric field enhanced-emission in the p⁺-n diode, where the junction barrier is much larger. The p⁺-n diode configuration allows the observation of a hole trap atE_t-E_v=0.87 eV in the n-GaN which is very likely related to the yellow luminescence band.