Preparation and optimization of a molybdenum electrode for CIGS solar cells

Abstract

Molybdenum (Mo) films were deposited by radio frequency (RF), direct current (DC) and mixed magnetron sputtering, respectively. With changing the deposition parameters including deposition pressure and power, the films show different surface morphology and crystallinity. Lower resistivity of the films is obtained in the DC mode and better reflectivity of the films is obtained in the RF mode. It is shown that the crystallinity increases when the deposition pressure decreases. The crystallinity and the grain size both increase as the deposition power increasing. The lowest resistivity of the single Mo film is 34×10-6 Ω·cm when the deposition pressure is 0.1 Pa and the deposition power is 300 W in the DC mode. In order to obtain lower resistivity, better adhesion and better reflectivity, bilayer films and tri-layer films were both deposited in different mode. They all show good adhesion and low resistivity. The Mo films deposited in mixed mode show better reflectivity. It is demonstrated that the resistivity of about 65×10-6 Ω·cm is achieved in DC/RF mode and the resistivity of about 61×10-6 Ω·cm is achieved in RF/DC/RF mode. And the tri-layer films achieved in RF/DC/RF mode have better reflectivity than bilayer films achieved in DC/RF mode. The tri-layer films achieved in RF/DC/RF mode is appropriate for using as the electrode of CIGS solar cells.

Effects of Bottom Layer Sputtering Pressures and Annealing Temperatures on the Microstructures, Electrical and Optical Properties of Mo Bilayer Films Deposited by RF/DC Magnetron Sputtering

“…However, fewer people focused on the influences of processing parameters on the properties of Mo bilayer films prepared by RF/DC sputtering method. Commonly, Mo films prepared by RF sputtering have better adhesion to the substrate and higher reflectance but lower conductivity than those prepared by DC sputtering under the same sputtering conditions, but the Mo films prepared by DC sputtering have better conductivity [16]. Actually, the reflectance of Mo back electrode is also very important to the Cu(In,Ga)Se 2 (CIGS), copper zinc tin sulphur (CZTS) and other solar cells, because higher reflectance can improve their photo-conversion efficiency [17].…”

Plasma etching and surface characteristics depending on the crystallinity of the BaTiO3 thin film

“…This demonstrates that the annealing process leads to crystallization of the previously non-crystallized regions in mainly the (110) orientation. However, no peaks are observed in the (100) and (210) orientations of the perovskite phase, which can be attributed to the specific method of deposition [25][26][27]. The peaks marked with red rectangles and blue circles in figure 1(a) are due to TiO 2 and Ti 2 O 3 , respectively, while the peak marked with a white diamond is due to the Si substrate [28,29].…”

Mo Contact via High-Power Impulse Magnetron Sputtering on Polyimide Substrate

“…Using the lower HiPIMS working pressures of 3 mTorr and 5 mTorr, excellent resistivity of 12.6 × 10 −6 Ω•cm and 18.3 × 10 −6 Ω•cm could be respectively obtained. Due to the increased carrier mobility, these results are significantly better than those derived using the DC sputtering conditions [31]. This is because the high coating power density and dissociation rate of HiPIMS make the structural characteristics and surface defects of the Mo films better than those resulting from DC sputtering and facilitate carrier movement.…”