Formation and Transient Photovoltaic Properties of ZnO/Si Isotype Heterojunctions by Magnetron Sputtering
The structural and electro-physical characteristics of ZnO/Si heterostructures deposited by the magnetron sputtering from aluminum-doped ZnO target are addressed. The film recrystallization and microcrystal structure restoration are observed. It is found
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1 Introduction The integration of thin films with Si technology implies serious limitations of the minimum thickness of the film, allowing to create an isotype heterojunction with high quality. This is a particularly competitive task as numerous thermal treatment steps are usually involved. One of the most important problems in this respect is the need to avoid the formation of large defect concentrations at the film/substrate boundary. It is known that zinc oxide exhibits unique properties, which make it interesting for study and numerous applications [1]. V. Melnik · B. Romanyuk (B) · V. Kladko · V. Popov · O. Gudymenko · O. Liubchenko · T. Sabov · O. Oberemok · O. Dubikovskyi · JU. Gomeniuk · O. Kosulya Lashkaryov Institute of Semiconductor Physics, Prospect Nauki, 41, Kiev 03028, Ukraine e-mail: [email protected] V. Melnik e-mail: [email protected] V. Kladko e-mail: [email protected] V. Popov e-mail: [email protected] O. Gudymenko e-mail: [email protected] O. Liubchenko e-mail: [email protected] T. Sabov e-mail: [email protected] O. Oberemok e-mail: [email protected] © Springer Nature Switzerland AG 2021 O. Fesenko and L. Yatsenko (eds.), Nanomaterials and Nanocomposites, Nanostructure Surfaces, and Their Applications, Springer Proceedings in Physics 246, https://doi.org/10.1007/978-3-030-51905-6_24
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One promising type of ZnO-based structures suitable for photovoltaic applications employs undoped ZnO layers grown on Si wafers [2]. Zinc oxide is also a piezoelectric and optical waveguide material, which was used in sensor and ultraviolet (UV) detector, light emitting diode (LED), surface acoustic wave (SAW), and solar cell technologies, as well as transparent electrodes, particularly, carrier-selective contacts with wide band gaps for Si heterojunction solar cells [3–9]. Zinc oxide was also extensively explored for using in transparent thin film transistors (TFTs) [10–12]. High optical transparency in the visible range and low resistivity make ZnO an important material for its using as heat mirrors in stoves, conducting coatings in aircraft glasses to avoid surface icing [13]. The native defects in ZnO, oxygen vacancies VO and zinc interstitials Zni , form donor levels in the forbidden gap, so that zinc oxide is naturally an n-type semiconductor [14]. The Si/ZnO heterojunction is also widely employed. The presence of SiOx native oxide and defects at the interface affects the charge carrier generation and recombination and drastically changes the electrical and photoelectric properties of the heterojunction. Physical properties of ZnO depend on growth method, impurities, temperature, and other factors, which in turn are important for the effective performance of practical devices. One important prerequisite for the LED applications is the ability to achieve n and p types of electrical conduction in ZnO [15]. This allowed to fabricate and realize p-n junction on ZnO and observe electroluminescence in the junction [16, 17]. However, as the acceptor impurities are hardly dissolved, it is
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