TEMPERATURE-DEPENDENCE OF INTERBAND-TRANSITIONS IN GAN GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

The interband transitions in single-crystal GaN films grown by metalorganic chemical vapor deposition (MOCVD) have been studied as a function of temperature (15≤T≤300 K) by reflectance and photoluminescence measurements. At low temperatures, well-resolved spectral features corresponding to the GaN band structure were observed. The energies of the excitonic interband Γ9V-Γ7C,Γ 7V (upper band)-Γ7C and Γ7V(lower band)-Γ7C transitions are found to be 3.485, 3.493, and 3.518 eV at 15 K, respectively, for the MOCVD GaN. The spectral features are broadened and shift to lower energy as temperature increases. At room temperature (300 K), the Γ9V-Γ7Cand Γ7V (upper band) -Γ7C transition energies of this wide band-gap material are determined to be 3.420 and 3.428 eV, respectively. The temperature dependence of these two transitions have been determined using the Varshni empirical relation. Our results yield E0(T)=3.486-8.32×10-4T2/(835.6+T) eV for the Γ9V-Γ7C transition and E0(T)=3.494-10.9×10-4T2/(1194.6+T) eV for the Γ7V (upper band) -Γ7C transition.© 1995 American Institute of Physics.