Dielectric constant of GaN thin films

질화갈륨 박막의 유전 상수

We measured the dielectr~c constant of undoped GaN thin films grown on (0001) sapphire substrates In 0.8 - 4.5 eV energy (276 - 1550 nm wavelength) range by spectroscopic ellipsometry. For more accurate data analysis we also performed X-ray diffraction, photolurninescence and Rutherford backscattering spectroscopy on samples. Data were analyzed with a four-phase model. The dielectric constant of GaN thin films was obtained not only in the transparent region but also around the absorption edge. Absorption edge energy, $3.3992{\pm}0.002$eV was determined from the obtained dielectric function.