Solar cells, depth profile

The chemical and electronic properties of elements at the interfaces between very thin films and bulk substrates are important in several technological areas, particularly microelectronics, sensors, catalysis, metal protection, and solar cells. To study conditions at an interface, depth profiling by ion bombardment is inadvisable, because both composition and chemical state can be altered by interaction with energetic positive ions. The normal procedure is, therefore, to start with a clean or other well-characterized substrate and deposit the thin film on to it slowly at a chosen temperature while XPS is used to monitor the composition and chemical state by recording selected characteristic spectra. The procedure continues until no further spectral changes occur, as a function of film thickness, of time elapsed since deposition, or of changes in substrate temperature. 

Depth scale calibration of an SIMS depth profile requires the determination of the sputter rate used for the analysis from the crater depth measurement. An analytical technique for depth scale calibration of SIMS depth profiles via an online crater depth measurement was developed by De Chambost and co-workers.103 The authors proposed an in situ crater depth measurement system based on a heterodyne laser interferometer mounted onto the CAMECA IMS Wf instrument. It was demonstrated that crater depths can be measured from the nm to p,m range with accuracy better than 5 % in different matrices whereas the reproducibility was determined as 1 %.103 SIMS depth profiling of CdTe based solar cells (with the CdTe/CdS/TCO structure) is utilized for growing studies of several matrix elements and impurities (Br, F, Na, Si, Sn, In, O, Cl, S and ) on sapphire substrates.104 The Sn02 layer was found to play an important role in preventing the diffusion of indium from the indium containing TCO layer. 

Figure 9.7 Depth profile of part of a solar cell system. (]. S. Becker and H. ]. Dietze, Int. ]. Mass Spectrom. Ion Proc. 197, 1(2000). Reproduced by permission of Elsevier.)...

Bulle-Lieuwma CWT, van Gennip WJH, van Duren JKJ, Jonkheijm P, Janssen RAJ, Niemantsverdriet JW (2003) Charaderization of polymer solar cells by TOF-SIMS depth profiling. Appl Surf Sci 203-204 547... 

Gastel, M., Brener, U., Holzbrecher, H., Becker, J.S., Dietze, H., Wagner, H. (1997) Depth profile analysis of thin film solar cells using SNMS and SIMS. Fresenius Journal of Analytical Chemistry, 358,207-210. 

Pisonero, J., Lobo, L., Bordel, N., Tempez, A., Bensaoula, A., Badi, N., Sanz Medel, A. (2010) Quantitative depth profile analysis of boron implanted silicon by pulsed radiofrequency glow discharge time-of-flight mass spectrometry. Solar Energy Mater. Solar Cells, 94, 1352-1357. 

Ellis-Gibbings L, Johansson V, Walsh RB, Kloo L, Quinton JS, Andersson GG (2012) Formation of N719 dye multilayers on dye sensitized solar cell photoelectrode surfaces investigated by direct determination of element concentration depth profiles. Langmuir 28(25) 9431-9439... 

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