Dr. Harry Efstathiadis
SUNY Albany
Dr. Efstathiadis is associate Professor at the College of Nanoscale Science and Engineering at the University at Albany SUNY.
His research is focused in thin film process development of a-Si: H, poly-Si, and Cu(In, Ga)Se2 using vacuum deposition methods,
chemical bath deposition of ZnS and CdS, and multilayer structures on glass and flexible metal substrates.
He is experienced in characterization of thin film surfaces, interfaces, and bulk optical,electrical, physical,
and chemical properties by optical-, electron-, ion-, and x-ray spectroscopies and electrical measurements.
His expertise includes reel-to-reel electropolishing and electrodeposition onmetal stripes for industrial production
of CIGS devices on metal flexible templates, screen printing andcharacterization including reliability of Ag paste
metal grids for CIGS- and Si-based PV devices.
Development of CuInGaSe2 and CuInAlSe2 Thin Films for Solar Cell Applications
Abstract: Polycrystalline thin film material based on CuIn1-xGaxSe2 (CIGS) is a promising candidate as an absorber material for
low-cost and high-efficiency photovoltaic (PV) devices. In this work power conversion efficiency of 9.9% was achieved with CIGS
thin films solar cell devices in which the absorber layer was deposited by thermal co-evaporation from single element sources.
Along other deposition techniques, the two-step process, in which the selenization step follows the sputtering step of metallic
precursors, seems to be a feasible technique for industrial production use. CuInGa and CuInAl precursor thin films were deposited
using simultaneously CuGa (75-25 at%) and In or Al 3?diameter target material by RF magnetron sputtering. The CuInGa precursor films
were deposited on Si, Mo/Si and glass substrates at -80 and room temperature and characterized for composition, crystalline phases,
morphology, and compositional depth uniformity. The effects gun power density, CuGa target quality and substrate temperatures on
resulting precursor film properties were investigated. Precursors films deposited at -80 have a smooth morphology with a
90% reduction in all roughness values and are more dense and homogeneous in structure compared to precursors deposited at room
temperature. CuInAl precursor films with varying Al/(In+Al) ratios were also co-sputtered onto Mo coated soda-lime glass substrates.
Metal precursor films were then selenized under vacuum conditions using thermally evaporated elemental selenium. The maximum device
efficiency measured was 5.2% under AM1.5 was for a device with ~2 at. % Al.