Is Carrier Mobility a Limiting Factor for Charge Transfer in Tio2/Si Devices? A Study by Transient Reflectance Spectroscopy

Ramsha Khan, Hannu Pasanen, Harri Ali-Löytty, Hussein Ayedh, Jesse Saari, Ville Vähänissi, Mika Valden, Hele Savin, Nikolai V. Tkachenko

Tutkimustuotos: LehtiartikkeliArticleScientificvertaisarvioitu

1 Sitaatiot (Scopus)
32 Lataukset (Pure)

Abstrakti

TiO 2 coatings are often deposited over silicon-based devices for surface passivation and corrosion protection. However, the charge transfer (CT) across the TiO 2/Si interface is critical as it may instigate potential losses and recombination of charge carriers in optoelectronic devices. Therefore, to investigate the CT across the TiO 2/Si interface, transient reflectance (TR) spectroscopy was employed as a contact-free method to evaluate the impact of interfacial SiO x, heat-treatments, and other phenomena on the CT. Thin-film interference model was adapted to separate signals for Si and TiO 2 and to estimate the number of transferred carriers. Charge transfer velocity was found to be 5.2 × 10 4 cm s −1 for TiO 2 heat-treated at 300 °C, and even faster for amorphous TiO 2 if the interfacial SiO x layer was removed using HF before TiO 2 deposition. However, the interface is easily oversaturated because of slow carrier diffusion in TiO 2 away from the TiO 2/Si interface. This inhibits CT, which could become an issue for heavily concentrated solar devices. Also, increasing the heat-treatment temperature from 300 °C to 550 °C has only little impact on the CT time but leads to reduced carrier lifetime of ¡3 ns in TiO 2 due to back recombination via the interfacial SiO x, which is detrimental to TiO 2/Si device performance.

AlkuperäiskieliEnglanti
Artikkeli102871
Sivumäärä12
JulkaisuSurfaces and Interfaces
Vuosikerta38
DOI - pysyväislinkit
TilaJulkaistu - kesäk. 2023
OKM-julkaisutyyppiA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

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