Impact of interfacial layer using ultra-thin SiO2 on electrical and structural characteristics of Gd2O3 MOS capacitor

• DOI: 10.1007/s10854-018-9847-9
• Publication Date: 2018-08-13T12:15:39Z
• Authors: Aysegul Kahraman; Umutcan Gurer; Ramazan Lok; Senol Kaya; Ercan Yilmaz
• Keywords: 02 engineering and technology; 0210 nano-technology

The aim of present study is to improve the quality of Gd2O3/p-Si MOS structure by reducing interface trap charge density. Therefore, the ultra-thin SiO2 layer was grown to high-k/Si interface. The effect of the post deposition annealing on the structural properties of the Gd2O3/SiO2 films and electrical characteristics of the Al/Gd2O3/SiO2/p-Si/Al were investigated for three different temperature. Besides, the effect of the series resistance and measurement frequency on the electrical characteristics of the p-MOS capacitors was examined in detail. 118 nm-thick Gd2O3 films were grown by RF magnetron sputtering following the 5 nm-thick SiO2 deposition on p type Si wafer by dry oxidation method. While the Gd2O3 monoclinic characteristic peaks were observed in the Gd2O3/SiO2/Si structures annealed at 600 °C and 800 °C, the XRD spectra of as-deposited and annealed at 400 °C sample pointed out Gd silicate formation. –Si, –O, –Gd, and –H bonds were defined in the FTIR spectra of all samples. The frequency dependent capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of Gd2O3/SiO2 MOS capacitor were measured. Strong accumulation capacitance values in these devices did not change significantly depending on frequency. Unlike from the MOS capacitor with as-deposited and annealed Gd2O3/SiO2 at 400 °C, the interface trap charge density $$({N_{it}})$$ increased with increasing voltage frequency for the samples annealed at 600 °C and 800 °C. No significant change in the border trap density $$({N_{bt}})$$ with increasing frequency was observed in the MOS capacitor except for as-deposited device. The barrier height $$({\Phi _B})$$ increased with increasing frequency for all Gd2O3/SiO2 MOS capacitors.