ZnO is a wide band gap, naturally n-type semiconductor with great promise for optoelectronic applications; the main obstacle yet to be overcome is p-type doping. Nitrogen, the most promising candidate currently being pursued as a dopant, has been predicted to preferentially incorporate into the ZnO lattice in the form of a N2 molecule at an O site when a plasma source is used, leading to compensation rather than p-type doping. We demonstrate this to be incorrect by using N K-edge x-ray absorption spectra and comparing them with first-principles calculations showing that nitrogen, in fact, incorporates substitutionally at O sites where it is expected to act as an acceptor. We also detect the formation of molecular nitrogen upon annealing. These results suggest that effective p-type doping of ZnO with N may be possible only for low-temperature growth processes.
Direct observation of nitrogen location in molecular beam epitaxy grown nitrogen-doped ZnO / P. Fons; H. Tampo; A.V. Kolobov; M.Ohkubo; S. Niki; J. Tominaga; R. Carboni; F. Boscherini; S. Friedrich. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 96:(2006), pp. 045504-1-045504-4. [10.1103/PhysRevLett.96.045504]
Direct observation of nitrogen location in molecular beam epitaxy grown nitrogen-doped ZnO
CARBONI, ROBERTA;BOSCHERINI, FEDERICO;
2006
Abstract
ZnO is a wide band gap, naturally n-type semiconductor with great promise for optoelectronic applications; the main obstacle yet to be overcome is p-type doping. Nitrogen, the most promising candidate currently being pursued as a dopant, has been predicted to preferentially incorporate into the ZnO lattice in the form of a N2 molecule at an O site when a plasma source is used, leading to compensation rather than p-type doping. We demonstrate this to be incorrect by using N K-edge x-ray absorption spectra and comparing them with first-principles calculations showing that nitrogen, in fact, incorporates substitutionally at O sites where it is expected to act as an acceptor. We also detect the formation of molecular nitrogen upon annealing. These results suggest that effective p-type doping of ZnO with N may be possible only for low-temperature growth processes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.