Interface properties of mixed (TiO 2) 1-x(Y 2O 3) x and (Ta 2O 5) 1-x(Y 2O 3) x (0 ≤ x ≤ 1) gate dielectrics on sulfur-passivated GaAs

T. Das, C. Mahata, S. Mallik, S. Varma, G. Sutradhar, P. K. Bose, C. K. Maiti

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Abstract

An experimental technique to reduce the growth of undesirable interface layer in high-k gate dielectrics is reported. Effects of mixing of TiO 2 and Ta 2O 5 in Y 2O 3 on the interface layer growth are studied in detail. Chemical composition and the interfacial properties of Y 2O 3 (TiO 2 and Ta 2O 5 mixed) ultra thin films prepared by RF sputtering on S-passivated GaAs are reported. It is shown that the formation of Ga-O bonding at the GaAs surface and As diffusion in the dielectric may effectively be controlled by mixing of TiO 2 and Ta 2O 5. Band gap (E g) of the mixed (TiO 2) 1-x(Y 2O 3) x and (Ta 2O 5) 1-x(Y 2O 3) x high-k gate dielectrics are found to be ∼5.30.05 and ∼5.50.05 eV, respectively. The Ta and Ti incorporated Y 2O 3 (Ta 2O 5) 1-x(Y 2O 3) x and (TiO 2) 1-x(Y 2O 3) x films on p-GaAs improve metal-oxide-semiconductor (MOS) capacitor characteristics such as interface state density, accumulation capacitance, hysteresis, and leakage current. The leakage current of ∼ 2.4 × 10 -6 Acm 2 at V g= V fb -1V was achieved for (TiO 2) 1-x(Y 2O 3) xGaAs gate stacks.

Original languageEnglish
Pages (from-to)H323-H328
JournalJournal of the Electrochemical Society
Volume159
Issue number3
DOIs
StatePublished - 2012

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