Influence of Ti doping on the band gap and thermal stability of ultrathin GeOfilms

Yong Cheng Yang, Yi He Tsai, Pratyay Amrit, Ting Yu Chen, Hui Ting Liu, Shu Jung Tang, Chun-Liang Lin*, Chao-Hsin Chien

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The thermal stability of the dielectric interfacial layer (IL) inside the metal-oxide-semiconductor field-effect transistor can affect the quality of the final products. One vital problem is whether the size and location of the band gap might be influenced by the annealing treatment. Here, we report the direct measurement of the band gap by scanning tunneling spectroscopy (STS) for ultrathin GeO x film (about 0.9 nm) and Ti-GeO x film (about 0.7 nm) grown on Ge substrates by atomic layer deposition as a dielectric IL. To examine the thermal stability, annealing treatment was performed for the films at 500 C. From the topography images, the root-mean-square roughness showed a difference of less than 0.03 nm. STS spectra show that the band gap is significantly modified after the annealing treatment for the case of GeO x film. Ultraviolet photoemission spectroscopy also confirms the shift of the valence band (VB) edge. For GeO x film doped with Ti for 30 s by sputtering, both the band gap and the VB edge remain unchanged after the annealing treatment. Our results show that Ti doping can improve the thermal stability of GeO x .

Original languageEnglish
Article number345102
Pages (from-to)1-7
Number of pages7
JournalJournal of Physics D: Applied Physics
Issue number34
StatePublished - Aug 2021


  • Ge oxides
  • atomic layer deposition (ALD)
  • band gap
  • microscopy/spectroscopy (STM/S)
  • scanning tunneling
  • ultraviolet photoemission spectroscopy (UPS)


Dive into the research topics of 'Influence of Ti doping on the band gap and thermal stability of ultrathin GeOfilms'. Together they form a unique fingerprint.

Cite this