Growth of TiO2 thin films on chemically textured Si for solar cell applications as a hole-blocking and antireflection layer

Autor: Ranveer Singh, Tapobrata Som, Mahesh Saini, Avanendra Singh, Mohit Kumar, Biswarup Satpati
Rok vydání: 2017
Předmět:
Zdroj: Applied Surface Science. 418:225-231
ISSN: 0169-4332
DOI: 10.1016/j.apsusc.2017.01.307
Popis: In this work, we investigate the broad-band photoabsorption of an n-TiO2 thin film and its hole-blocking properties when a heterostructure is grown on a chemically textured p-Si substrate. We demonstrate that average specular reflectance of conformally grown TiO2 thin films on chemically prepared pyramidally textured Si substrates can be brought down to ∼0.2% (in the wavelength range of 300–1200 nm), which increases up to ∼0.53% after annealing at 673 K in air for 1 h. X-ray diffraction data reveal the amorphous nature of as-grown TiO2 thin films which undergoes a transition to a crystalline one after annealing. In addition, bulk current-voltage characteristics show that the leakage current increases after annealing which corroborates well a with change in the band gap, as is measured from the optical absorption spectra, due to a transition from amorphous to crystalline (anatase phase) of TiO2. Moreover, TiO2/Si heterojunction allows the transport of electrons but blocks the transport of holes. The present results are not only important for the fundamental understanding of the charge transport across TiO2/Si heterostructures but also to design hole-blocking solar cells.
Databáze: OpenAIRE
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