Mar 13, 2016 - larity parameter p and the infinitely thick film resistivity p 0 are found to be strongly ... the electrical properties of thin films (Neugebauer 1964).
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The effect of substrate temperature on the electrical resistivity of thin manganese films
This content has been downloaded from IOPscience. Please scroll down to see the full text. 1981 J. Phys. D: Appl. Phys. 14 1125 (http://iopscience.iop.org/0022-3727/14/6/020) View the table of contents for this issue, or go to the journal homepage for more
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J. Phys. D: Appl. Phys., 14 (1981) 1125-7. Printed in Great Britain
The effect of substrate temperature on the electrical resistivity of thin manganese films S M Shivaprasad and M A Angadi Thin Film Laboratory, Department of Physics, Karnatak University, Dharwad 580 003, (Karnatak) India Received 13 June 1980, in final form 5 January 1981 Abstract. The effectof the substrate temperature on the electricalresistivity of thin manganese films, over the thickness range from 100 to loo0 A is reported. The specularity parameter p and the infinitely thick film resistivity p 0 are found to be strongly dependent on the substrate temperature.
The deposition parameters such as (a) substrate temperature T,,(b) substrate material, (c) deposition rate, and ( d ) pressure in the vacuum chamber during film deposition play an importantrole in determining the electrical properties of thin films (Neugebauer 1964). Though some work has been reported for semiconducting films (Sloope and Tiller 1962, 1965, Weisberg 1967), the work on metallic films is not exhaustive. It is generally known that for films prepared by evaporation, the substrate temperature is one of the most important parameters which influences bothstructuraland electrical properties of metallic films. We have already reported on the electrical resistivity (Shivaprasad et a1 1980b), and the the effect of deposition rate on the electrical resistivity (Shivaprasad and Angadi 1980)of thinmanganese films. In this note, we report on theeffect of Ts on theresistivity of manganese films grown at T,= 22 "C, 100 "C and 160°C overthethicknessrange 100-1000 A. The experimental details are given elsewhere (Shivaprasad et al 1980a). However, the substrate was heated by a radiant heater and the temperature was recorded by a chromel-alumel thermocouple. The thin film resistivity can be expressed as (Larson 1971) plpo= 1 +(3/8h)(l -P)
h>O.l
(1)
where p is the resistivity of the film, p0 is the background resistivity, h is the ratio of the film thickness t to the background electron mean free path l, and p is the specularity parameter. Figure 1 shows the thickness dependence of resistivity curves for different substrate temperatures. It is evident from the figure that the resistivity of films decreases with increase in T,. The higher Ts may result in increased surface mobility of adatoms and clustersduringdeposition and hence inlarger crystallite sizes. So, the decrease in resistivity due to the increase in Ts may be attributed to the increase in crystallite size. A similar change in resistivity at higher T, has been reported in titanium (Igasaki and Mitsuhashi 1978) and palladium (Murr 1971). Figure 2 shows a pt versus t graph for films deposited at different substrate temperatures. The intercepts on the y-axis and the slopes of these graphs give us Z(l - p ) and PO, 0022-3727/81/061125+03 $01.50
01981 The Institute of Physics
1125
1126
S M Shivaprasad and M A Angadi
- 1200
400 I 400
I
0
I
I
t (h,
800
1
li
Figure 1. Thickness dependence of resistivitycurves for thin manganese films for experimental points: 0 22 "C, 0 100 "C, x 160 " C ; different substrate temperatures TB; the theoretical curves due to Fuchs-Sondheimer theory are shown by continuous curves.
Figure 2. Graphs of pt versus t for three different substrate temperatures: 0 22 "c, 0 100"C, x 160°C.
respectively. Using these values of [(l -p) and PO, we have tried to fit the theoretical curve by giving different values of p ranging from 0 to 1, in equation (1). The best fits for different curves are achieved by the values o f p listed in table 1. With these values ofp, the electron mean free pathsare calculated. The values in table 1 indicate that the surface Table 1. Values of resistivity, specularity parameter and electron mean free path for films deposited at various temperatures. Substrate temperature Ts ("C)
250
22 100 160
Infinitely thick film resistivity PO cm)
Specularity parameter
373
0.35 0.55 0.60
184
p
Electron mean free path
[ ( l -P)
(A)
[(A) 1200 1163 262
780 640 105
Electrical sesistiuitymanganese of jilms thin
1127
of the films becomes smoother (i.e. p increases) as we go to higher T,, while the background electron mean free path I remains unaltered. For many films (Jain and Chander 1968, Bist and Srivastava 1973, Curzon and Singh 1979, Shivaprasad et a1 1980b) the p0 estimated by the p versus t curve is quite high compared to the bulk value, which is due to inherent film defects (Chopra 1969). So, our present measurements on thin manganese films show that it is possible to minimise the incorporated defects, by a proper choice of T,. However, our explanations are to be examined by structural and otherstudies, which will be reported in a future communication.
Acknowledgments We thankMr PV Ashrit andMr measurements.
LA Udachanfortheirhelp
in theexperimental
References Bist B M S and Srivastava O N 1973 Thin Solid Films 18 71 Chopra K L 1969 Thin Film Phenomena (New York: McGraw Hill) p 171 Curzon A E and Singh 0 1979 Thin Solid Films 57 157 Igasaki Y and Mitsuhashi H 1978 Thin Solid Films 51 33 Jain S C and Chander R 1968 J. Appl. Phys. 39 5343 Larson D 1971 Physics of Thin Films eds M H Francombe and R W Hoffman (New York: Academic Press) p 85 Murr L E 1971 Thin Solid Films 7 101 Neugebauer C A 1964 Physics of Thin Films v01 2, eds G Hass and R E Thun (New York: Academic Press) p 10 Shivaprasad S M and Angadi M A 1980 J. Phys. D: Appl. Phys. 13 L157 Shivaprasad S M, Angadi M A and Udachan L A 1980a Thin Solid Films 71 L1 Shivaprasad S M, Ashrit P V and Angadi M A 1980b Phys. Stat. Solidi 60 A K159 Sloope B W and Tiller C 0 1962 J. Appl. Phys. 33 3458 -1965 J. Appl. Phys. 36 3174 Weisberg L R 1967 J. Appl. Phys. 38 4537
