N doping using N2O and NO sources: From the viewpoint of ZnO

Abstract

A study of N doping using N2O and NO sources on ZnO, which may prove important for the N doping of oxide materials, was performed by investigating the doping processes of N atoms by each source together with the various properties for the grown N doped ZnO films. N2O was employed as the radio-frequency (rf) plasma source to produce radical N2* species that could effectively incorporate N atoms above 1020 cm−3 into ZnO, which was similar to N doping using N2 as the source. In contrast, it was found that the ZnO films doped with a N concentration above 1020 cm−3 were easily obtained using a gas flow of NO. The N concentration could be controlled systematically by the simultaneous gas flow of NO and O2 sources. The basis of N doping using a NO source could be related to the free radical characteristic of NO molecular. This idea was proposed from the results that the N concentrations doped to ZnO using a gas flow of N2O and N2, which have the characteristics of neutral and nonreactive molecules in air, were in the ranges from 1018 to 1019 cm−3. Further, our investigations clarified that the structural, optical, and electrical properties for the N doped ZnO films were not quite dependent on the N2, N2O and NO sources used as N dopants. This work proposes that NO is a promising source as a N dopant that can be employed without using a rf plasma source in the application of physical vapor deposition techniques that are indispensable for producing radical N2* species through a rf plasma source to achieve the efficient incorporation of N atoms when N2 and N2O sources are used as N dopants.

High temperature dehydrogenation for realization of nitrogen-doped p-type ZnO

“…The N concentration for as-gown ZnO:N films is about 2.36 Â 10 21 , which was computed from measuring peak area in the X-ray photoelectron spectroscopy. This is consistent with some early reports with similar growth conditions, where an effectively incorporation of N atoms in the film at above 10 20 -10 21 /cm 3 have been reported [13]. Moreover, high concentrations of hydrogen and carbon are detected by SIMS analysis, which suggested the unintentional incorporation of H and C into films from the MO sources and their byproducts.…”

ZnO light-emitting diode grown by plasma-assisted metal organic chemical vapor deposition

“…[2][3][4] Traditionally, N 2 has been used as the doping source, although the equilibrium solubility of N is expected to be low. 2 In order to increase the N solubility, various exotic approaches have been applied such as using NO, 5,6 N 2 O, 6 their combination, 7 or NH 3 , 8 as the source. It has been suggested 9 that the use of NO may reduce the concentration of undesirable substitutional N 2 molecular donors.…”

Realization of intrinsic p-type ZnO thin films by metal organic chemical vapor deposition

“…2a, though 5 sccm of N 2 O gas was introduced into the chamber during growth, the nitrogen intensity was well below the SIMS sensitivity limit (N count was too low to be detected). Matsui et al 18 have previously shown that the solubility of nitrogen is low due to the poor dissociation process of N 2 O at the low temperature of 350°C. Thus, the N concentration in the ZnO thin film grown with N 2 O flow should be quite low.…”