Single material TiO 2 thin film by atomic layer deposition for antireflection and surface passivation applications on p-type c-Si

Tsung Cheng Chen*, Tsuo Chuan Yang, Hsyi En Cheng, Ing Song Yu, Zu-Po Yang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

A thin film deposited on the front surface of solar cell plays an important role in reducing the reflection of incident light and providing surface passivation. Although ultrathin TiO 2 films have shown excellent performance of surface passivation, simultaneously serving both functions is hindered by the crystallization issue, which can degrade the passivation quality of TiO 2 film, as the film thickness is over certain value (few nanometer only). Here we showed that both functions can be satisfied by single material of titanium oxide film through atomic layer deposition at low temperatures. By varying deposition temperatures from 80 to 200 °C, the TiO 2 film deposited at 80 °C can maintain its amorphous phase up to the thickness of 114 nm. In addition, the optimal thickness for antireflection calculated by OPAL 2 is 61 nm, meaning that amorphous TiO 2 film to provide antireflection and surface passivation can be achieved. The passivation quality is verified by minority carrier lifetime measurement using photo-conductance decay method and presented the ultralow surface recombination velocity of 8.7 cm/s. Furthermore, the passivation mechanism is investigated by X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS), in which the absence of crystalline issue is confirm and both chemical passivation (due to H termination) and field effect passivation (due to residual Cl atoms) are associated with the improvement of passivation quality. A post deposition anneal is conducted on the TiO 2 film deposited at 80 °C. The results present that extra thermal budgets can ruin the passivation quality, which is explicated by the TiO 2 crystallization as the temperature exceeding 350 °C from the XRD measurements, and by the descending of Cl atom (also field effect passivation) as increasing of the annealing temperature from the SIMS measurements.

Original languageEnglish
Pages (from-to)121-127
Number of pages7
JournalApplied Surface Science
Volume451
DOIs
StatePublished - 1 Sep 2018

Keywords

  • Antireflection coating
  • Atomic layer deposition
  • Surface passivation
  • Titanium oxide

Fingerprint Dive into the research topics of 'Single material TiO <sub>2</sub> thin film by atomic layer deposition for antireflection and surface passivation applications on p-type c-Si'. Together they form a unique fingerprint.

Cite this