Formation and study of p–i–n structures based on two-phase hydrogenated silicon with a germanium layer in the i-type region

• Published in: Semiconductors (Woodbury, N.Y.) N.Y.), 2017-10, Vol.51 (10), p.1370-1376
• Main Authors: Krivyakin, G. K., Volodin, V. A., Shklyaev, A. A., Mortet, V., More-Chevalier, J., Ashcheulov, P., Remes, Z., Stuchliková, T. H., Stuchlik, J.
• Format: Article
• Language: English
• Subjects: Carrier recombination; CHARGE CARRIERS; CHEMICAL VAPOR DEPOSITION; Clusters; Current carriers; DEPOSITS; ELECTRICAL FAULTS; Electromagnetic absorption; ELECTRON MICROSCOPY; Epitaxy; Fabrication; GERMANIUM; Magnetic Materials; Magnetism; MATERIALS SCIENCE; MOLECULAR BEAM EPITAXY; Molecular structure; Photovoltaic cells; Physics; Physics and Astronomy; Plasma enhanced chemical vapor deposition; QUANTUM DOTS; Short circuits; Silicon; SOLAR CELLS; Testing of Materials and Structures; Thickness; Treatment
• ISSN: 1063-7826; 1090-6479
• DOI: 10.1134/S1063782617100128

Four pairs of p–i–n structures based on polymorphous Si:H ( pm -Si:H) are fabricated by the method of plasma-enhanced chemical vapor deposition. The structures in each pair are grown on the same substrate so that one of them does not contain Ge in the i -type layer while the other structure contains Ge deposited by molecular-beam epitaxy as a layer with a thickness of 10 nm. The pair differ from one another in terms of the substrate temperature during Ge deposition; these temperatures are 300, 350, 400, and 450°C. The data of electron microscopy show that the structures formed at 300°C contain Ge nanocrystals ( nc -Ge) nucleated at nanocrystalline inclusions at the pm -Si:H surface. The nc -Ge concentration increases as the temperature is raised. The study of the current–voltage characteristics show that the presence of Ge in the i -type layer decreases the density of the short-circuit current in p–i–n structures when they are used as solar cells, whereas these layers give rise to an increase in current at a reverse bias under illumination. The obtained results are consistent with known data for structures with Ge clusters in Si; according to these data, Ge clusters increase the coefficient of light absorption but they also increase the rate of charge-carrier recombination.