Near-infrared absorption of CuGaTe2and CuGaSe2thin films

✍ Scribed by B. A. Mansour; S. H. Moustafa; M. A. El-Hagary

• Publisher: Springer US
• Year: 1995
• Tongue: English
• Weight: 227 KB
• Volume: 6
• Category: Article
• ISSN: 0957-4522
• DOI: 10.1007/bf00188193

✦ Synopsis

Near-infrared absorption spectra of p-type CuGaTe2 and CuGaSe2 thin films deposited by thermal evaporation were measured at room temperature. Two structures were found in the spectra in the photon energy range from hv=0.4-1.5 eV. One of them is the free carrier absorption below 0.6 eV in which the absorption Coefficient increases as the third power of the wavelength. Another structure seems from carrier concentration dependences to be associated with an absorption band at hv ~ 0.95 eV for CuGaTe2 and 0.75 eV for CuGaSe2 due to transition from a lower-lying valence band to an upper one. From the optical absorption data also, the ionization energy of the acceptor level was found to be 190 meV for CuGaTe2 and 280 meV for CuGaSe2.