TY - JOUR
T1 - Growth of N-doped and Ga + N-codoped ZnO films by radical source molecular beam epitaxy
AU - Nakahara, K.
AU - Takasu, H.
AU - Fons, P.
AU - Yamada, A.
AU - Iwata, K.
AU - Matsubara, K.
AU - Hunger, R.
AU - Niki, S.
N1 - Funding Information:
We would like to extend our thanks to Dr. Shibata for useful discussions. This work was partly supported by NEDO, the New Energy and industrial technologies Development Organization, Japan.
PY - 2002/4
Y1 - 2002/4
N2 - It has been theoretically predicted that the codoping of an acceptor (nitrogen) and a donor (aluminium, gallium, indium) in a 2: 1 ratio will enable the fabrication of low resistivity p-type ZnO due to reduction of the Madelung energy making the nitrogen acceptor energy level shallower. We have been growing N-doped and Ga + N codoped ZnO films by radical-source molecular beam epitaxy. Nitrogen and oxygen radicals were separately supplied via radio-frequency radical cells. Nitrogen did not incorporate in ZnO films at the high substrate temperature of 600°C. Lower substrate temperatures were necessary for nitrogen incorporation. From the fact that the nitrogen concentration also depended on the Zn fluxes, it is concluded that Zn-rich conditions are indispensable for nitrogen doping. The presence of Ga was observed to enhance nitrogen incorporation, one of the predicted effects of codoping. However, high Ga concentrations were found to lead to formation of the additional phase of ZnGa2O4 in ZnO films.
AB - It has been theoretically predicted that the codoping of an acceptor (nitrogen) and a donor (aluminium, gallium, indium) in a 2: 1 ratio will enable the fabrication of low resistivity p-type ZnO due to reduction of the Madelung energy making the nitrogen acceptor energy level shallower. We have been growing N-doped and Ga + N codoped ZnO films by radical-source molecular beam epitaxy. Nitrogen and oxygen radicals were separately supplied via radio-frequency radical cells. Nitrogen did not incorporate in ZnO films at the high substrate temperature of 600°C. Lower substrate temperatures were necessary for nitrogen incorporation. From the fact that the nitrogen concentration also depended on the Zn fluxes, it is concluded that Zn-rich conditions are indispensable for nitrogen doping. The presence of Ga was observed to enhance nitrogen incorporation, one of the predicted effects of codoping. However, high Ga concentrations were found to lead to formation of the additional phase of ZnGa2O4 in ZnO films.
KW - A1. Doping
KW - A3. Molecular beam epitaxy
KW - B2. Semiconducting II-VI materials
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U2 - 10.1016/S0022-0248(01)01952-2
DO - 10.1016/S0022-0248(01)01952-2
M3 - Article
AN - SCOPUS:0036531359
SN - 0022-0248
VL - 237-239
SP - 503
EP - 508
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
IS - 1-4
ER -