The effect of deposition environment conditions on the electrical and structural properties of deposited
Lead iodide PbI
Deposition of a layer of PbI
Although the application of the external magnetic field during the electrodeposition process has gained a lot of attraction [
In view of this situation we have investigated the structural and electrical properties dependence of the deposited layer on the deposition conditions (including applying homogeneous external magnetic field, room light illumination, and darkness) in order to understand the transformation accompanying the growth from solution.
Polycrystalline PbI
The average area of platelet was calculated from the surface photo using optical microscope type (NiKon-Cclipsc/ME 600) equipped with digital camera type (DYM 1200F). For such calculations we chose the largest platelet and eight points on the contour. This step was repeated four times. The structural properties of the layers were investigated using X-ray diffraction system (Lab X-XRD-6000/Shimadzu) which has the following characteristics: source: radiation of CuK
The electrical resistivity (
The optical micrographs shown in Figures
Optical micrographs of the PbI
Table
The average grain area of different PbI
samples | Deposition conditions | Average platelets area |
---|---|---|
1 | Dark without applied magnetic field | 180.75 |
2 | Dark with applied magnetic field | 78.48 |
3 | light without applied magnetic field | 23.11 |
4 | light with applied magnetic field | 15.584 |
From the X-ray diffrograms the planes orientations were determined. Besides, grain size, number of layers (NL), and microstress (
XRD patterns for sample deposited in (a) dark without magnetic field, (b) dark with magnetic field, and (c) light without magnetic field, in light with magnetic field.
The corresponding data, that is, the interplanar distance, average grain size, number of layers, and microstress are presented in Table
Analysis of the XRD study of undoped PbI
Sample | 2? (degree) | (hkl) | Grain size A | NL | |
---|---|---|---|---|---|
Sample 1 | 12.7159 | 6.95896 | (001) | 682.6201 | 160 |
25.5079 | 3.48924 | (002) | 563.7793 | 206 | |
38.6427 | 2.32813 | (003) | 474.6347 | 244 | |
52.3991 | 1.74474 | (004) | 805.2267 | 144 | |
Sample 2 | 12.732 | 6.9472 | (001) | 644.573 | 164 |
25.4861 | 3.49217 | (002) | 560.3059 | 176 | |
38.6385 | 2.32838 | (003) | 390.0919 | 254 | |
52.3645 | 1.74581 | (004) | 925.2506 | 107 | |
Sample 3 | 12.7173 | 6.9552 | (001) | 620.2268 | 161 |
25.4451 | 3.4977 | (002) | 542.9319 | 173 | |
38.5992 | 2.33066 | (003) | 585.751 | 160 | |
52.3258 | 1.74701 | (004) | 1004.105 | 93 | |
Sample 4 | 12.7157 | 6.95607 | (001) | 501.9222 | 192 |
25.5132 | 3.48852 | (002) | 540.2273 | 178 | |
38.6713 | 2.32648 | (003) | 531.3026 | 182 | |
52.3824 | 1.74526 | (004) | 958.8356 | 100 |
The number of deposited layers (NL) under light and magnetic field has the higher value, while sample deposited in dark without magnetic field has the smallest value NL.
Figures
The variation in the plane grain size with the platelets area.
Electrical conductivity was calculated from the current-voltage characteristics. Figures
Ohmic behavior of both dark and photocurrents of the different samples.
Table
Figure
Dark conductivity versus platelet area.
The photoconductivity in PbI
Variation in the conductivities versus platelet area.
It has been shown that polycrystalline lead iodide layers with interesting structural properties can be prepared by means of a simple solution growth methods. The deposited layers are made of hexagonal platelets parallel to the substrata planes. Their sizes differ from a few micrometers to a tens micrometers. All XRD patterns had the same peaks. Neither on the crystal structure nor on the texture, lighting or magnetic field effect has been observed. All layers irrespective of deposition parameters develop a preferred (001) plane. The grain size increases with the increase of the platelets area when deposition is carried out in darkness (682.6201 A