Dielectric Function Study on Zincblende CdSe Film
- We present the dielectric function spectra of CdSe at room temperature between 0.7 and 9 eV obtained by using vacuum ultra-violet spectroscopic ellipsometry (SE). We observed new critical point (CP) energies, whose observation by SE has not been reported so far, in the spectral range above 6 eV. The values of the CP energy were determined by using a standard analytic line shape analysis. With those data, we calculated the band structure of CdSe by using the linear augmented Slater-type orbital (LASTO) method within the local density approximation, where an empirical self-energy correction is added to the conduction bands to reproduce the observed band gaps at room temperature. From the comparison of the data and theory, we could identify the measured CP transition energies as $E_0$, $E_0+Delta_0$, $E_1$, $E_1+Delta_1$, $E_2$, $E_2+Delta_2$, $E_0'$, $E_0'+Delta_0'$, $E_0'+Delta_0'+Delta_0$ and $E_1'$ in the 0.7 $sim$ 9 eV region.
- Keywords: Ellipsometry, CdSe, Bandgap, Band structure