Optical Absorption and Photoluminescence Studies of n-type GaN

The Si-doping dependence of absorption coefficient and photoluminescence (PL) spectra of GaN grown by metalorganic chemical vapor deposition (MOCVD) was studied at room temperature. Band gap narrowing and band tailing effect were observed in the absorption spectra of GaN samples with high carrier concentration. A clear red shift and broadening of the PL emission peak were observed with increasing dopant concentration, which could also be attributed to the band tailing effect. This study shows that the band tailing effect plays an important role in determining the optical properties of Si-doped GaN.