Comments on the article: “Enhancing the photovoltaic effect in the infrared region by germanium quantum dots inserted in the intrinsic region of a silicon p-i-n diode with nanostructure” by H. M. Tawancy (Journal of Materials Science DOI: 10.1007/s10853-011-5728-9)

Abstract

This comment letter report on a critical reading of an article published in Journal of Materials Science [1]. As stated in the acknowledgements, the silicon-based solar cells described in the article under question were contractually fabricated at the Institut d’Electronique Fondamentale, by using the technological facilities of the University Technology Center (CTU IEF-Minerve) of the University Paris Sud, France. The fabrication of prototype devices on request of external research institutions is part of the current assignments of this Center. The corresponding invoice was received from the author of Ref [1] in April, 2009. Using our previous know-how in epitaxial growth, a number of structures have been fabricated, consisting of a stack of Ge quantum dots, a Si layer and a highly doped Si layer, as described in Fig. 1 of ref. [1]. The solar cell devices based on these structures were completed with back and front contacts, as seen in Fig. 8 of Ref [1]. In addition, structural and optical routine characterizations were done in order to calibrate the areal quantum dot density and check the quality of the grown material, consisting in scanning electron microscopy imaging, and photoluminescence (PL) measurements made at room temperature. In collaboration with Prof. O. Aboelfotoh, we also checked the current voltage characteristics of the whole devices in the dark and under AM 1.5 standard illumination by using the dedicated facility of the Laboratoire de Genie Electrique de Paris, France. These devices and attached data were finally provided in 2010 to the King Fahd University of Petroleum & Minerals, Saudi Arabia. At this step, Dr H.M. Tawancy was of course free to act in his own way, like publishing results obtained from these devices. The corresponding article, entitled ‘‘Enhancing the photovoltaic effect in the infrared region by germanium