Engineering of Optical and Electrical Properties of Electrodeposited Highly Doped Al:ZnO and In:ZnO for Cost-Effective Photovoltaic Device Technology

Abstract

Resistivity and transparency of zinc-oxide layers (ZnO) for chalcopyrite photovoltaic technology applications were engineered by activation of the Burstein–Moss (BM) effect at high concentrations of aluminium (Al) and indium (In) dopant. The Al:ZnO and In:ZnO layers were processed by cost-effective, large-area, fast-rate electrochemical deposition techniques from aqueous solution of zinc nitrate (Zn(NO3)2) and dopant trichlorides, at negative electrochemical potential of EC = (−0.8)–(−1.2) V, moderate temperature of 80 °C, and solute dopant concentrations of AlCl3 and InCl3 up to 20 and 15 mM, respectively. Both Al:ZnO and In:ZnO layers were deposited on Mo/glass substrates with ZnO and ZnO/ZnSe buffers (Al:ZnO/ZnO/Mo/glass, In:ZnO/ZnO/ZnSe/Mo/glass), respectively. Based on the band-gap energy broadening of Al:ZnO and In:ZnO originated by the BM effect, maximum carrier concentrations of the order 1020 and 1021 cm−3, respectively, were determined by optical characterization techniques. The (electrical) resistivity values of Al:ZnO calculated from optical measurements were commensurate with the results of electrical measurements (10−4 Ohm×cm). In both cases (Al:ZnO and In:ZnO), calibration of carrier density in dependence of solute dopant concentration (AlCl3 and InCl3) was accomplished. The p–n junctions of Au/In:ZnO/ZnO/ZnSe/CIGS/Mo on glass substrate exhibited current–voltage (I–V) characteristics competing with those of crystalline silicon (c-Si) solar cells.

Optical Characterization of ALD-Coated Nanoporous Alumina Structures: Effect of Sample Geometry or Coated Layer Material

“…Different techniques can be used for the optical characterization of thin films [45][46][47], with spectroscopy ellipsometry (SE) measurements being one of the most surface-sensitive optical tools for the characterization of substrates and overlayers used for different sensor applications [48][49][50]. SE is a precise and accurate surface technique for characterizing substrates and overlayers, commonly used for the determination of basic optical parameters of thin films such as the refractive index (n) and the extinction coefficient (k), two parameters related to the interaction between materials and incident light and associated with refraction or absorption, respectively, as well as the dielectric constant (real (ε r ) and imaginary (ε i ) parts).…”

Optical Properties of TiO2 Doped ZnO-PVA Nanocomposites

“…ZnO is used as a filler since its potential applied in optoelectronic applications has attracted attention with a wide band gap Eg (at 300K) = 3.4 eV with a relatively short wavelength region, a relatively large exciton binding energy of 60 meV, and semiconductors in groups II-VI that crystallize in cubic or hexagonal/wurtzite structures. In the case of ZnO, most of it is in the form of wurtzite crystals [9]. Besides that, the use of ZnO as a filler in ZnO-PVA nanocomposites is due to its non-toxic nature, chemical stability, and strong luminescent material, as well as improving the performance of PVA.…”

Investigation of Photoluminescence and Optoelectronics Properties of Transition Metal-Doped ZnO Thin Films

“…It exhibits a stable hexagonal wurtzite crystal structure at standard ambient temperature [1]. It is a very effective transparent conducting oxide (TCO) material, possessing a favorable bandgap of 3.37 eV at standard room temperature [2]. Additionally, the light transmittance through them within the visible spectrum is enhanced as the wavelength increases at first.…”