ti substituted nano-crystalline [cu.sub.3]n thin films.

by:ZHENHUA     2020-03-15
Abstract Ti:[Cu. sub. 3]
Si of n rf plasma (111)
, Quartz and slide substrate, by dc rf sputtering in molecular nitrogen environment.
Ti: structural properties [Cu. sub. 3]
N film studied with X-
Ray diffraction (XRD)analysis.
Xrdmeasures show peak proximity (100)and(200)
Diffraction line of cubic inverse[ReO. sub. 3]structure of[Cu. sub. 3]N. The Ti:[Cu. sub. 3]N nano-
Crystal size in range 22-27 nm.
Lattice constant expansion reflects the production of excessive nitrogen caused by the incorporation of Ti.
The surface morphology showed that Nrichness inhibited the growth of the grain.
Due to the higher N concentration and quantum size effect, the optical absorption spectrum is significantly transferred to higher energy at the absorption edge.
Light emission (PL)
The measurement results show the gap N excess and Ti impurity yield, respectively.
Thermal stability of TheTi :[Cu. sub. 3]
N films annealing at 300 and 400 [degrees]
C improved compared to Ti free [Cu. sub. 3]N films.
Key words N excess, Ti incorporation, quantum size effect, introduction of shallow deep level [Cu. sub. 3]
N film has been successfully used for manufacturing-
Primary optical recording medium ,(1-3)
For writing through a maskless-free laser (4)
As the insulation barrier of the magnetic tunnel junction. (5)
In fact, nitrogen copper is heat stable and can be broken down into copper and nitrogen.
The decomposition temperature is about 250 [degrees]C. (6), (7)
The potential interest in the reactive magnetic-controlled sputtering process depends on the possibility of producing films with new properties, significantly different from the corresponding equilibrium body.
This is especially true when considering nanotechnology.
Crystal and Nano
A composite film that can be formed. (8), (9)Nano-
Crystal lenses are very interesting research materials, because the basic properties of matter change when the carrier is limited to quantum size. (10)
There is an easy way to measure the optical constants, depending on the measurement of the single transmission ratio.
Multi-Crystal Ti: Reflection index n and extinction coefficient k and thickness d [Cu. sub. 3]
The N film studied here is only determined from the transmission ratio data by using the bir method and the code described by Birgin et al. (11)
This method implements a complex optical equation as shown below12)and Swanepoel. (13)
The transmission ratio of the film absorbing film deposited on a thick transparent substrate is T by: T = T ([lambda], s([lambda]), d, n([lambda]), k([lambda]))=A\'x/B\'-C\'x + D\'[x. sup. 2], (1)where [
Mathematical expressions that cannot be reproduced in ASCII]
Where s is the refractive index of the substrate, n and k are the real and imaginary parts of the refractive index of the film, and d is the thickness of the film ,[lambda]
Is the wavelength of light, and [alpha]
It is the absorption coefficient of the membrane. Birgin et al. (11)
The continuous least squares solution to the estimation problem is proposed (d, n, and k)of Minimize [
Mathematical expressions that cannot be reproduced in ASCII](2)
Some physical restrictions.
The quartz substrate is thick enough, thus eliminating the interference effect generated by multiple reflections in the substrate.
In the PUMA code, the experimental transmission ratio data is compared with the theoretical value.
The difference between these two values is minimized until the best solution for refractive index n, extinction coefficient k, and film thickness d is obtained. Poelman et al. (14)
The PUMA method was reviewed and tested, and its excellent estimation of the Optical constants of the film was demonstrated.
Most of the publications deal with the representation of the sputtering deposition and [physical properties] of the reactive magnetic controlCu. sub. 3]
N film as a function of the deposition parameters: nitrogen (partial)
Pressure in the gas mixture ,(15-17)
Substrate temperature ,(7), (18)
And splash power. (19), (20)Although [Cu. sub. 3]
N has been extensively studied and there is little information in the literature about transition metalsdoped [CU. sub. 3]N.
Recently, some [based on ternarycompound [Cu. sub. 3]
Grow N; (Pd, Cu)N, (21)(Ti, Cu)N,(22)and (Ag, Cu)N. (23)Also, Moreno-Armenta et al. (24)
The metal insertion is studied theoretically (
M = nickel, copper, zinc, Pd, Ag and Cd)
In the center [Cu. sub. 3]
N units on the electronic structure.
In this study, Ti was included in the compartment[ReO. sub. 3]structure of [Cu. sub. 3]N.
The selection of Ti is due to the strong reaction of this element to nitrogen and the local increase of nitrogen concentration in [Cu. sub. 3]N films. (Ti, Cu)
Ncoatings are formed by reactive DC sputtering in purenitrogen environment.
The structure, morphology, resistivity, optical energy gap and thermal stability of the deposited film were studied.
Experimental Copper and nitrogen films with titanium content were deposited by using advanced DC radio frequency sputtering method from a single multi-component target in TiCu (13 at. % Ti)
Ultrasonic cleaning Si (111)
In the presence of a nitrogen atmosphere, single crystal, quartz, and slide substrates at a sputtering power of 60 and 80G.
Sputtering power [
Less than or equal to]
100 W is the best choice for the production of near chemical metrology [Cu. sub. 3]
N, the film formed at a power greater than 100w is a mixed phase of Cu and [Cu. sub. 3]N. (19), (20)
The studio of the sputtering system pumps down through Rotary pumps and saturated molecular pumps, allowing the base pressure to be less than 7 x [10. sup. -4]
Maintain Pato.
Total air pressure, substrate temperature and target-
The substrate distance is maintained at 1. 0 Pa, 150[degrees]
Cand 19 cm, respectively.
The structure was characterized in situ by X-ray diffraction (Siemens D5000)with a Cu [K. sub. [varies]]
2 radiation sources in [theta]scan mode.
Average size of Nanocrystallites (D)
Estimated from half the maximum width of the strongest peak with the revised scherrer formula ,(25)
The peak widening D = 0 caused by residual stress in the film was ignored. 94[lambda]/([beta]-b)Cos[theta], (3)where [beta]
Is the FWHM of the diffraction peak ,[lambda]
What is the wavelength of the event Cu [K. sub. [varies]]X-ray< [theta]
It is the Cape of Prague, and B is the standard instrument widening (0. 08[degrees]).
The morphology and chemical composition of the film were determined by coupled scanning electron microscopy and energy dispersion X-
Rayspectrometer (
SEM/EDX for Philips XL30).
Optical Study by measuring the transmission ratio of the wavelength region 300-
With a 1100 nm splitter (Shimadzu, UV-
1700 pharmaceutical specifications)
At room temperature
With these measurements, we can get a complex refractive index. n. sub. c]
= N ik, where n and k are the refractive index and reflection coefficient, respectively.
By pushing the outside of the absorbing edge line to the horizontal coordinates to obtain the optical energy gap energy gas with low energy.
Light Lighting (PL)
Measured at room temperature using Xe 350 nm lamps as excitation sources.
The resistivity of the film at room temperature was measured by a four-point probe method.
Results and discussion of structural properties in figure 1
1 shows the X-ray spectrum of as deposition ti: [Cu. sub. 3]N films on Si(111)
One is grown with a 60w sputtering power, and the other is grown with a 80w sputtering power.
Only [movie]Cu. sub. 3]
Correspondence between N and peak (100)and(200)reflections.
A rough estimate of the average crystal size was obtained from [Cu. sub. 3]N (100)
The diffraction peaks and sputtering power are calculated using the improved Scherrer formula.
This shows that for the sputtering power of 60 W and 80 w, the size of the crystal is 22 and 27 nm, respectively. The Ti:[Cu. sub. 3]
N movies are made up of moviescrystallites. [
Figure 1 slightly]
In most of the works, [chemical metrology]Cu. sub. 3]
The N film is derived from X-ray diffraction data (
Change of grid parameters). (7),(15-17), (26)
The lattice constant is estimated from the position [Cu. sub. 3]N (100)
Diffraction peaks.
The evolution of the lattice constant of the film is due to the change of nitrogen chemical metrology. (23)
However, there is currently no information about the location of the excess Atlanta. Cu. sub. 3]N unit cell. (23)
Due to the sensitivity of the chemical composition to the representation method, the lattice constant [Cu. sub. 3]
Nis is considered to be a good qualitative criterion for determining a combination. The Ti:[Cu. sub. 3]
The N lattice constant is 0. 3828 and 0.
The sputtering power of 60w and 80w is 3851nm, respectively. TheTi:[Cu. sub. 3]
The N lattice constant is higher than the theoretical value (i. e. , 0. 3815 nm). (17)
Compare the peak position of Ti: [Cu. sub. 3]
N film and standard JCPDS (Card No. 02-1156)
Free data for Ti [Cu. sub. 3]N in Table 1.
Therefore, for the sputtering power of 60w and 80 w, Ti :[Cu. sub. 3]
Over-chemical metrology of N films (N-rich).
Adding titaniumCu. sub. 3]
N pieces save cube counter[ReO. sub. 3]structure of [Cu. sub. 3]N (Fig. 1).
In addition, the addition of the Titanic (100)
The direction that happens compared to Tifree [Cu. sub. 3]N with (111)
Preferred direction. (7), (22), (23),(27), (28)Fan et al. (22)
The preferred orientation of copper and nitrogen films is proposed (111)
For film without doping (100)for 1 at. %Ti-doped films.
Of the deposition conditions tested in this study, only [Cu. sub. 3]
N phase was detected by X-ray diffraction.
The film does not have any diffraction lines of titanium or titanium nitrogen.
Titanium atoms are not separated only in another phase, because the reduction dynamics of titanium are stronger than that of copper. .
Titanium addition indicates the transformation [Cu. sub. 3]
N diffraction peaks to lower angle positions compared to titanium
Free film, indicating an increase in lattice constants.
The titanium atom is then placed in the nitrogen-copper network. The [Cu. sub. 3]
N structure displays a vacant site in the cell center. (6), (23)
Ti atomic scanning is not entirely located in the center of the chemometric ratio [Cu. sub. 3]N cell.
In fact, the highest value of the lattice constant of ti: [Cu. sub. 3]N films (0. 3851 nm)
Calculated value still below [Cu. sub. 3]MN (
M = copper, zinc, Pd and Ag). (24)
Since the radius of the titanium atom is higher than M = Cu, Zn, Pd and Ag atoms, the titanium atom replaces the vacancy in [Cu. sub. 3]
N cells centered on titanium may not be considered further.
Similar to adding silver atoms in [Cu. sub. 3]N cell, (23)
Here, the formation of copper in [Cu. sub. 3]
N cells replaced by Ti atoms are considered to explain the lattice constants measured.
[Titanium Company]Cu. sub. 3]
Ncell is a buffer that causes more nitrogen concentration in the film.
This is consistent with the fact that all the films discussed before are excessivestoichiometric.
Surface Morphology Ti: surface morphology [Cu. sub. 3]
N films prepared at two different sputtering power are shown in the figure. 2.
As can be seen, the film has a clear particle structure and a sharp particle boundary.
With respect to 60 w, the particle size of the film decreases when the sputtering power of sample preparation is 80 w, which is due to the enhanced surface diffusion of atoms at higher sputtering power. The Tidoped [Cu. sub. 3]
N pieces are spherical-
Form of contrast with Tifree [Cu. sub. 3]
Pyramid Filmlike grains. (22)TheTi:[Cu. sub. 3]
N films are similar to those with regional transitions (T)
The microstructure of the Thornton model. (29)
The surface of the T-zone film is smooth and dense. (30)[
Figure 2:
The particle size of the film is determined according to the SEM image.
According to the particle size determination, the radius of each spherical particle along the XY plane is determined.
Calculate the effective granularity by taking the average of 10-
There are 12 particles in each SEM image.
Effective granularity of Ti :[Cu. sub. 3]
For the sputtering power of 60 W and 80 W, the N lattice is 108 and 58 nm, respectively.
The size of the apparent particles decreases with the increase of the consumption power.
People believe that the extra nitrogen atoms around the titanium atom ([TiN. sub. x]precipitation)
Inhibit grain growth.
It can be seen from the SEM image that the particle size and nitrogen concentration (
Or the price constant)
The opposite trend.
To estimate the atomic Ti: Cu ratio in the film, we make the following assumption: * the difference in the throwing distance of any sputtering component in the target
The substrate spacing, the nitrogen dynamics differences on the target surface of any component, the difference in angle distribution of any sputtering component, and the difference in adhesion coefficient of any sputtering component on the substrate were excluded.
Atomic Ti: Cu ratio can be roughly calculated using [
Mathematical expressions that cannot be reproduced in ASCII](4)where [c. sub. b. sup. Ti]
Ti concentration on the target surface. [
Mathematical expressions that cannot be reproduced in ASCII]and [
Mathematical expressions that cannot be reproduced in ASCII]
For [reasons], the rates of sputtering of Ti and Cu areN. sub. 2. sup. +]
Ion bombardment (
Like two independent [N. sup. +]ions).
The sputtering rate depends on the energy and angle distribution of the sputtering atom, so Y (E, [theta])= Y(E, 0)* S([theta]), (5)
Where E is the energy of the ion, approximately equal [eV. sub. d]and [theta]
Is the spray angle of the sputtering atom relative to the surface normal.
The energy-related part is given by Eckstein et al. (31)as Y(E)= [qs. sub. n. sup. KrC]([epsilon])(E/[E. sub. th]-1[). sup. [mu]]/[lambda]+ (E/[E. sub. th]-1[). sup. [mu]], (6)q, [E. sub. th], [mu], and [lambda]
This is the material-
Dependency parameters listed in table 2. [E. sub. th]and[s. sub. n. sup. KrC]([epsilon])
The threshold energy of the sputtering and the nuclear stop power is respectively.
Yamamura et al. Proposed the angular distribution of artificial satellites. (32)
Follow the relationship of type S ([theta])= Cos[theta](1 + [beta][Cos. sup. 2][theta]), (7)where [beta]
Is a fitting parameter.
The fitting parameters depend on the quality and binding energy, mass and ion energy of the target material.
Can be expressed [beta]= BLnQ -[B. sub. c]and Q = [M. sub. t]E/[M. sub. g][E. sub. sb],(8)where [M. sub. t]
What is the mass of atoms and [E. sub. sb]
Binding energy of sputtering materials (Table 2).
Value of B and [B. sub. c]
Approximate 0 respectively. 488 and 2. 44. Using theEq.
4 under almost normal injection, the Ti: Cu atomic ratio at different nitrogen pressures was evaluated ~ 0. 068.
Due to the uncertainty of the EDX method in determining the thermal instability of nitrogen concentration and copper nitrogen, this paper only introduces the Ti: Cu atomic ratio.
Atomic Ti: Cu ratio of deposited Ti: [Cu. sub. 3]N films on Si(111)
The average evaluation of the substrate is be0. 067 and 0.
The sputtering power of 60w and 80w is 074, respectively.
Ti: Cu ratio is usually lower than the atomic Ti: Cu ratio [Ti. sub. 13][Cu. sub. 87], namely, 0. 15.
Ti: there is a good consistency between the experimental value and the calculated value of the Cu atomic ratio.
As we all know, the sputtering yield ratio of Ti to Cu is close to 0.
6 calculated values based on the equation.
All transmit power.
In addition, when Ti is splashed in [N. sub. 2]
In the atmosphere, the decay rate is reduced due to the fact that a portion of Ti on the target surface is nitrated. (33)
This effect is weak for Cu because of Cu-N bonding.
After a period of sputtering, the Ti: Cu ratio on the target surface will reach a balance, so that the ratio of the sputtering yield of the two materials will be less than their ratio in the body target.
Therefore, the difference between the target and the composition in the film is likely to be caused by their different throw distance, nitrogen dynamics, the angular distribution of any sputtering composition, and different absorption rates on the surface of the film.
In addition, the energy neutral N ion from the plasma atmosphere, reflected by the target dissociation, may be the source of Ti
Sputtering and defects of InTi: [Cu. sub. 3]
N films about the target composition. In as-
Deposited thin film Ti can attract N to enter [Cu. sub. 3]
Direct Ti-N lattice
N chemical binding and solubility in [by increasing N]Cu. sub. 3]
N g, as discussed by Ding and others. (34)
The latter contribution is not included and only the former contribution is considered.
We assume that the amount of N attracted by the chemical bond in the film is first, N-
The enrichment of the absorption process leads to the formation of the electron receptor center associated with the gap nitrogen excess. Band-
The gap can be obvious from 2. 79 to 3.
34 eV, hole-compliant-
Filling effect of Valance band. (37)
This phenomenon may lead to degradation near the edge, widening the valence band and band (Burstein-Moss shift). (38)Second, nano-
Crystal size of Ti :[Cu. sub. 3]
N leads to transitions between discrete levels caused by quantum confinement effects. Ifthe Ti:[Cu. sub. 3]N nano-
The crystal size is the order of magnitude of the radius of Bohrexciton, then it corresponds to the intermediate restricted area of Efros et al.
A model describing the relationship between quantitative energy levels and crystal size (39)[E. sub. g]= [E. sub. gb]+ ([pi]h[). sup. 2]/2[R. sup. 2]m -2. 438[e. sup. 2]/[epsilon]R, (11)
Among them, m is the effective quality of the carrier ,[E. sub. gb]
The average radius of R is bulk energy gap. crystallite, [E. sub. g]
Is the energy of the electronic transition between the conduction band and the quantum state in the valence band, and [epsilon]
Is the semiconductor dielectric constant.
Quantum confinement effect and gap Nexcess lead to a significant widening of the energy gap of Ti: [Cu. sub. 3]
Comparison between N and Ti free [Cu. sub. 3]N.
According to Eq.
11 and crystal size, expected-
The film deposited at a sputtering power of 80w is less than 60 w.
However, the energy gap widening due to N richness overcomes
With respect to 60 w, the crystal growth of the film deposited at the sputtering power of 80 w.
Room temperature light (PL)
Measurement results :[Cu. sub. 3]
As shown in figure N. 7.
In addition to band-edge emission at 447 and 375 nm, it is related to as films grown at 60 and 80 W sputtering power, respectively;
There are two re-
ForTi: [emission mechanism]Cu. sub. 3]N films;
First, as described in ,(16)
The gap nitrogen oxide is used as the center of the electron receptor.
PL peaks of films grown at 486 and 411 nmfor as at the sputtering power of 60 and 80 W, respectively, in relation to the recipient\'s redistributed bandemission.
N receptor energy ,[E. sub. A]
Can be estimated by the following equation (40): [
Figure 7 Slightly][E. sub. A]= [E. sub. g]-[E. sub. PL]+ [k. sub. B]T/2, (12)where [k. sub. B]
T represents the boerzman constant and the absolute temperature, respectively.
Using the relevant energy gap at room temperature,E. sub. A]
At 60 and 80w respectively, the films grown are estimated to be 245 and 328 meV.
Therefore, the excess of gap N indicates the shallow host center.
The second mechanism measured by PL may be due to the doping of Ti and its response defect state.
Due to the Ti defect center, different PL peaks of as-grown films are around 669 and 701 nmare, respectively, and the sputtering power is 60 and 80 W, respectively.
The Ti defect state generates a deep energy level forbidden energy gap.
Ti: electrical properties resistivity at room temperature [Cu. sub. 3]
The film deposited on the slide substrate is 530 and 490 [mu][OMEGA]
60w and 80w respectively.
The crystalline quality of the sample prepared at the sputtering power of 80w is higher than that of the sample grown at 60w (see XRD in Fig. 1). It is obvious;
The resistivity of the former film is lower than that of the latter film.
Electric display movie
Metal behavior.
The addition of Ti-to [Cu. sub. 3]N-
At room temperature, the resistivity based on the film is significantly reduced.
According to the deposition conditions, the resistivity [Cu. sub. 3]
Pearson reports N films (17)is
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