Abstract：TiO$_{2}$ deposited at extremely low temperature of 120$^\circ\!$C by atomic layer deposition is inserted between metal and n-Ge to relieve the Fermi level pinning. X-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy indicate that the lower deposition temperature tends to effectively eliminate the formation of GeO$_{x}$ to reduce the tunneling resistance. Compared with TiO$_{2}$ deposited at higher temperature of 250$^\circ\!$C, there are more oxygen vacancies in lower-temperature-deposited TiO$_{2}$, which will dope TiO$_{2}$ contributing to the lower tunneling resistance. Al/TiO$_{2}$/n-Ge metal-insulator-semiconductor diodes with 2 nm 120$^\circ\!$C deposited TiO$_{2}$ achieves 2496 times of current density at $-$0.1 V compared with the device without the TiO$_{2}$ interface layer case, and is 8.85 times larger than that with 250$^\circ\!$C deposited TiO$_{2}$. Thus inserting extremely low temperature deposited TiO$_{2}$ to depin the Fermi level for n-Ge may be a better choice.
Kita K, Wang S K, Yoshida M, Lee C H, Nagashio K, Nishimura T, Toriumi A 2009 Electron Devices Meeting, IEEE International (Baltimore, MD, USA 7–9 December 2009) p 693
Figgemeiera E, Kylberga W, Constablea E, Scarisoreanub M, Alexandrescub R, Morjanb I, Birjegab R, Popovicib E, Fleacab C, Gavrila F L and Prodan G 2007 Appl. Surf. Sci.254 1037
2018, Vol. 35 
