High Efficiency Copper Indium Gallium DiSelenide (CIGS) by High Power Impulse Magnetron Sputtering (HIPIMS): A Promising
- PDF / 822,409 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 29 Downloads / 266 Views
1210-Q06-09
High efficiency Copper Indium Gallium Diselenide (CIGS) by High Power Impulse Magnetron Sputtering (HIPIMS): A promising & scalable application in thin-film photovoltaics Ankush Halbe1, Paul Johnson1, Shen Jackson1, Robert Weiss1, Upendra Avachat1, Alex Welsh1 and Arutiun P. Ehiasarian2 1
DayStar Technologies Inc, 2972 Stender way, Santa Clara CA 94040, USA Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield, S1 1WB, UK
2
ABSTRACT A novel method to deposit Copper Indium Gallium Diselenide (CIGS) using High Power Impulse Magnetron Sputtering (HIPIMS) was demonstrated and compared to the existing DC magnetron sputtering process. The metal-ion assisted thin-film growth inherent to a HIPIMS deposition process was used to advantage in depositing CIGS films. The HIPIMS plasma was characterized by measuring ion currents on a Langmuir probe placed into the plasma sufficiently close to the substrate. The high density plasma consisting of both metal and metal ions resulted in CIGS thin-film solar cells of superior conversion efficiencies (~13%) as compared to conventional DC magnetron sputtering (~10%). The efficiency enhancement was attributed to the improvement in the shunt resistance of the solar cell which corresponds to the increase in the density of the CIGS layer. Furthermore, it was also possible to grow large grained CIGS (~1 micron) with high mobility metal-ions from the HIPIMS process. The scalability potential of the HIPIMS CIGS process was also demonstrated by running a 1.5 m long Copper-Indium-Gallium rotatable in a selenium environment using a HIPIMS power supply. The cylindrical magnetron was run at an average power of 7.8 KW and peak powers of as much as 300 KW with controlled arcing. The existence of a HIPIMS plasma was confirmed by the ion currents on the Langmuir probe and the metal signals from a Plasma Emission Monitor (PEM). INTRODUCTION Thin-film solar cells based on Cu(In,Ga)Se2 (CIGS) have the advantage of low production costs and high conversion efficiencies [1]. Sputtering has been successfully demonstrated as one of the techniques to deposit CIGS films and has been applied to its large area in-line manufacturing [2,3]. This paper introduces the applicability of a modern sputtering technique called High Power Impulse Magnetron Sputtering (HIPIMS) to the deposition of CIGS thin-film layers. HIPIMS was introduced by Kuznetsov, et al., in 1999 as a technique that can produce a highly ionized flux of sputtered material [4]. This allows thin-film growth through a dense plasma with a high metal vapor ionization degree (up to 70% for Cu) [4]. This deposition technique has a distinct advantage of producing smoother, denser films of enhanced crystallinity as compared to DC magnetron sputtering. In traditional magnetron sputtering, it is difficult to achieve a dense plasma since the power applied is eventually limited by the cooling capacity of the target. This problem is overcome in HIPIMS by applying power to the target in the form of
high energy pulses of
Data Loading...
