Hall effect of copper nitride thin films

Abstract

The Hall effect of copper nitride (Cu 3 N) thin films was investigated in our work. Cu 3 N films were deposited on glass substrates by radio-frequency (RF) magnetron sputtering at different temperatures using pure copper as the sputtering target. The Hall coefficients of the films are demonstrated to be dependent on the deposition gas flow rate and the measuring temperature. Both the Hall coefficient and resistance of the Cu 3 N films increase with the nitrogen gas flow rate at room temperature, while the Hall mobility and the carrier density of the films decrease. As the temperature changed from 100 K to 300 K, the Hall coefficient and the resistivity of the films decreased, while the carrier density increased and Hall mobility shows no great change. The energy band gap of the Cu 3 N films deduced from the curve of the common logarithm of the Hall coefficient against 1/T is 1.17 -1.31 eV.The interest in copper nitride thin film had been growing in recent years due to its potential applications as write-once optical recording media [1] and precursor material for microscopic copper lines by maskless laser writing [2,3]. Copper nitride (Cu 3 N) is one of the important covalent metal nitride compounds and has been scarcely studied. The decomposition of this material into elements due to low thermal stability [4] suggests its possible use in metallization reactions [5], which could be of significant importance in the electronics industry, for instance, the feasibility of using this film to generate metal lines by maskless laser writing was explored recently [2]. Although Cu 3 N film could have many technological applications, few papers are available concerning its physical properties and the correlation between the chemical bonding and the physical properties. As a semiconductor material, more studies are needed. The Hall effect is a useful way to characterize the semiconductor materials, by which the carrier density and mobility can be measured. In device technology, Hall effect devices are widely used in the fields of measuring, automatization, information technology, etc.Various methods had been employed to obtain copper nitride films, such as RF-sputtering [6, 7], RF-plasma chemical reactor [8,9] and reactive pulsed laser deposition [10]. In these papers some physical and chemical properties of the copper nitride thin films have been studied. Herein, we firstly investigated the Hall effect of the Cu 3 N films prepared by reactive RF-sputtering deposition. ExperimentCopper nitride films were prepared by a reactive radio-frequency (RF) magnetron sputtering system. The sputtering target is made of oxygen-free copper with a purity of 99.9%. Commercial glass sheets as substrates were ultrasonically cleaned in acetone. The working gas was a mixture of 99.999% pure Ar and

Free-carrier contribution to the optical response of N-rich Cu3N thin films

“…It is worthwhile to mention here that our results contrast somehow with those reported by Yue et al [12,40] using Hall measurements, suggesting that the Cu 3 N shows an n-type semiconductor behaviour. In our opinion the divergences found in the behaviour of the material should be explained in terms of difference in film stoichiometry.…”

Electronic structure of copper nitrides as a function of nitrogen content

“…All samples exhibit a negative S coefficient which decreases from -5 uV/K to -50 uV/K with rising nitrogen concentration from 26 ± 2 to 33 ± 2 at.%. The negative sign of S indicates that the majority of the carriers must be electrons, being consistent with previously reported Hall effect data [23,28], The relatively small S value for the stoichiometric film might indicate that electron and hole carrier densities are almost compensated, as expected for an intrinsic semiconductor. For N-rich samples the absolute value of S, \S\, remarkably increases with rising nitrogen content, being up to one order of magnitude higher for the sample containing 33 at.% of nitrogen than for the stoichiometric one.…”

“…Experimental data [27] have revealed that for films sputtered under the same conditions, extra nitrogen (or at least a high fraction of it) incorporates in the film in interstitial positions forming a solid solution and expanding the crystal lattice in comparison to stoichiometric Cu 3 N. Moreover, spectroscopic ellipsometry and infrared absorption measurements carried out on N-rich Cu 3 N films have clearly indicated the presence of a free-carrier contribution in the optical spectra that has been related to the N excess [26]. The origin and nature of those extra carriers could not be elucidated in that work, partly due to the difficulty of carrying out reliable Hall measurements and the dispersion of so far reported data [23,28], In order to clarify the experimental situation and to assess the electronic role of the excess N in Cu 3 N experiments: electrical conductivity, spectroscopic ellipsometry at several temperatures and [23,28], that have not, so far, provided conclusive results. In fact, it has been claimed that Seebeck coefficient measurements often offer better reproducibility [29] than Hall Effect experiments.…”

Effect of Sputtering Power on the Physical Properties of Cu3N films Formed by DC Magnetron Sputtering

“…The achieved electrical resistivity of the films formed at the sputtering power of 75 Watts was in good agreement with the rf magnetron sputtered films. [9] The dependence of optical transmittance on the wavelength of the Cu 3 N films formed at different sputtering powers is shown in Figure 4. The optical transmittance of the films (wavelength .…”