Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 14: Preparation and characterization
HL 14.1: Vortrag
Dienstag, 24. März 2009, 09:30–09:45, BEY 154
XPS and NEXAFS Studies of Nitrogen Incorporated into ZnO During Epitaxial Film Growth — •Patrick Hoffmann and Christian Pettenkofer — Helmholtzzentrum Berlin, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
The wide band gap semiconductor ZnO (gap=3.4eV) is heavily n-doped by nature. In the last years it has been shown that ZnO can be p doped by incorporation of nitrogen. Investigations have shown that nitrogen can replace oxygen (NO, p doping), but can also be incorporated as molecular N2 ([N2]O, n doping), and can be bonded to oxygen.
In this work, the ZnO films are grown by metal-organic MBE (MOMBE) on sapphire substrate (r plane). Nitrogen is supplied by an ion source using pure nitrogen (N2) and nitrous oxide (N2O). Additionally, a mass filter between the ion source and the sample can be used to reduce the influence of the neutrals (e.g. N2), and to select certain ions and ion fractions (e.g. N2+, N+).
Our investigation was focussed on the chemical nature of the incorporated nitrogen. Therefore, nitrogen molecules (N2+) and nitrogen radicals (N+) have been implanted into the ZnO. The obtained films were investigated by XPS and NEXAFS. A comparison of the differently prepared films permits the assignment of photoemission peaks to chemical compounds of the nitrogen. Further investigations using N2O as nitrogen source, showed a different composition of the chemical states of the incorporated nitrogen.