Doğru Balbaşı, Çiğdem
CdZnTe is an II-VI group semiconductor material with significant properties used in many critical industrial applications, such as photovoltaic devices, photodiodes, photoconductors, room temperature gamma-ray spectroscopy, X-ray imaging, and infrared detectors. In Particular, CdZnTe is a promising material for solar cell application as an absorber layer due to its direct tunable bandgap property, high atomic number with strong absorption, excellent optoelectronic properties, and long-term stability. However, manufacturing CdZnTe-based solar cells has been a challenge, with minimum improvement recorded over the years. Therefore, four main topics about CdZnTe thin films were studied in this dissertation: (a) growth mechanism and material optimization of CdZnTe thin films by using various investigative characterization techniques, (b) understanding the surface and interface chemical compositional properties and optical dielectric response of CdZnTe thin films, (c) fabrication and electrical characterization of CdS/CdZnTe device structure with thin absorber layer (<2.0 μm) deposited at low substrate temperatures with reduced post-deposition processes, and (d) a detailed electrical analysis of the CdZnTe/Si structure for possible device applications. In this dissertation, high-quality CdZnTe thin films were fabricated using a thermal evaporation method with uniform component distribution, which was controlled by utilizing CdZnTe single crystal pieces as source material. Additionally, post-deposition processes such as annealing and CdCl2 treatment steps were applied. As a result, improved material properties and enhanced device performance of CdZnTe thin films were obtained. After a careful characterization of material and surface properties, thin heterojunction CdS/CdZnTe and CdZnTe/Si devices were fabricated successfully. It is worth noting that semitransparent thin CdZnTe films (≤2.0 µm) had a transmittance value greater than 75% in the near-infrared region, around 1000 nm. Finally, the operation and performance of the CdZnTe-based devices were investigated, and challenges encountered in the development of these devices were explained in detail.


Growth and optical characterization of Sn0.6Sb0.4Se layer single crystals for optoelectronic applications
Bektas, T.; Terlemezoğlu, Makbule; Surucu, O.; Isik, M.; Parlak, Mehmet (2022-04-01)
© 2021SnSe compound is an attractive semiconductor material due to its usage in photovoltaic applications. The substitution of Sb in the SnSe compound presents a remarkable advantage especially in point of tuning optical characteristics. The present paper reports the structural and optical properties of Sn1-xSbxSe (x = 0.4) layered single crystals grown by the vertical Bridgman method. To the best of our knowledge, this work is the first investigation of the Sn0.6Sb0.4Se crystal grown with the vertical Brid...
Structural characterization of intrinsic a-Si:H thin films for silicon heterojunction solar cells
Pehlivan, O.; Yilmaz, O.; Kodolbas, A. O.; Duygulu, O.; Tomak, Mehmet (2013-01-01)
We have utilized ex-situ spectroscopic ellipsometry and HRTEM to characterize the optical and structural properties of intrinsic a-Si:H thin layer that plays a key role for the improvement of the open circuit voltage in silicon heterojunction solar cells. Intrinsic a-Si:H films were deposited on (100) p-type CZ silicon wafers by using Plasma Enhanced Chemical Vapor Deposition (PECVD) technique at 225 degrees C substrate temperature and deposition time ranges from 15 s to 1800 s. Observed changes in the imag...
Effects of Substrate Temperature on material characteristics of sputtered Aluminum doped ZnO thin films
Bayraklı, Özge; Emir, Cansu; Güllü, Hasan Hüseyin; Parlak, Mehmet (null; 2016-09-23)
Transparent conductive layers (TCOs) attract the attention in opto-electronic and photovoltaic device applications due to their conductivity and transparency characteristics in the visible region of the solar spectrum. There are various TCO thin film layers, and indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) are the most popular thin films such as the desired material characteristics of SnO2and ZnO, respectively. In literature, the works indicated that the characteristics of these films can be c...
Efficient Light Trapping in Inverted Nanopyramid Thin Crystalline Silicon Membranes for Solar Cell Applications
MAVROKEFALOS, Anastassios; HAN, Sang Eon; Yerci, Selçuk; Branham, Matthew S.; CHEN, Gang (2012-06-01)
Thin-film crystalline silicon (c-Si) solar cells with light-trapping structures can enhance light absorption within the semiconductor absorber layer and reduce material usage. Here we demonstrate that an inverted nanopyramid light-trapping scheme for c-Si thin films, fabricated at wafer scale via a low-cost wet etching process, significantly enhances absorption within the c-Si layer. A broadband enhancement in absorptance that approaches the Yablo-novitch limit (Yablo-novitch, E. J. Opt. Soc. Am. 1987, 72, ...
Investigation of material properties of magnetron sputtered CuAg-In-Se thin films
Güllü, Hasan Hüseyin; Parlak, Mehmet (null; 2016-09-23)
Thin films of copper based chalcopyrite absorber materials are attracting the attention of many researchers because of their favorable optoelectronic properties and good stability makes them suitable for photovoltaic and optoelectronic device applications. These compounds are particularly suitable for making p-n hetero-junctions with the II-VI compounds. Therefore, the utilization of I-III-VI2 group of chalcopyrite semiconductors has been reported in the literature for application in thin film solar cells. ...
Citation Formats
Ç. Doğru Balbaşı, “GROWTH, CHARACTERIZATION AND DEVICE APPLICATIONS OF CADMIUM ZINC TELLURIDE THIN FILMS,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.