Conductivity type conversion of p-type CuInSe2 due to hydrogenation

The surface of p-type CuInSe2 single crystals prior to and after low energy hydrogen ion implantation at increased substrate temperature has been investigated by X-ray photoelectron spectroscopy (XPS) and Raman measurements. A shift of the Fermi-level by 500 meV closer to the conduction band after the hydrogen exposure has been observed for CuInSe2, oxidized by storage in air. The same behavior was observed for a clean surface prepared in ultra-high vacuum (UHV) by cleavage of CuInSe2. This observation supports the previously suggested type conversion from p- to n-type of the surface of CuInSe2. The conversion is explained by the passivation of Cu vacancies and hydrogen on and interstitial site. For the oxidized sample, the re-activation of oxygen passivated Se vacancies might influence the type conversion additionally. Raman spectroscopy did not reveal any lattice damage after implantation at 300 degreesC sample temperature. (C) 2001 Elsevier Science B.V. All rights reserved.