Structural, optical and electrical properties of high energy irradiated Cl-VPE grown gallium nitride

The effect of 80 MeV Si (fluences of 1011, 1012, 1013 and 1014 cm−2) on the structural and optical properties of chloride vapour phase epitaxy (Cl-VPE) grown unintentionally doped n-type gallium nitride (GaN) epitaxial layers have been studied by Raman scattering, high-resolution XRD, photoluminescence (PL), UV absorption and Hall measurement techniques. The behaviour of Raman shift for E2(high) and A1(LO) modes of GaN layers have been discussed. New peaks have been observed at the fluences 1013 and 1014 cm−2. Band tailing effect has been observed in the optical absorption spectra of GaN samples. Broadening of the PL emission peak were observed with increasing fluence concentration, which could be attributed to the band tailing effect which plays an important role in determining the optical properties of Si irradiated GaN layers. It is found that the irradiation induces lattice-disordering, decrease in the electron mobility and carrier concentration compared to as-grown samples.