Electrical characteristics of metal-dielectric-metal and metal-dielectric-semiconductor structures based on electron beam evaporated Y2O3, Ta2O5 and Al2O3 thin film

Abstract

This work examines the electrical properties of metal-dielectric-semiconductor (Au/Ti–D–pSi) and metal-dielectric-metal (Au/Ti–D–Pt/Ti–pSi) capacitors which incorporate as dielectrics Y2O3, Al2O3 and Ta2O5 films evaporated by an electron beam at room temperature. The emphasis of the results is twofold: the first is the high quality of the investigated films as evidenced by the small measured values of loss factor, flatband voltages, and surface states density as well as the low dispersion of the relative dielectric constants. The second is an analytical procedure for discrimination of current flow mechanisms, under different regimes of applied voltage. A detailed study of the power exponent parameter α=d(Log I)/d(Log V) was found to be superior to conventional graphical representation of I–V data. The dominant mechanisms of charge transport through the metal-dielectric-metal structures was found to be the Schottky emission for Y2O3 and Al2O3 at low electrical fields. For structures with Y2O3 and Ta2O5 films operating in the high field regime, the charge transport mechanism is mainly space charge limited current.

Dielectric function of amorphous tantalum oxide from the far infrared to the deep ultraviolet spectral region measured by spectroscopic ellipsometry

“…3 Thin films of tantalum oxide are also employed as an ion conductor in electrochromic devices. 4,5 Known as a material with high static dielectric constant and with good electrical insulating properties, tantalum oxide has the potential for microelectronic applications as a capacitor and gate material, thereby replacing silicon dioxide in metal-insulator-metal [6][7][8][9][10][11] or metal-insulator-semiconductor [6][7][8][9][10][12][13][14][15][16][17] structures as well as in large-scale integrated circuits for dynamic random access memories. 6 Sputter-deposited thin films tend to show film porosity, which affects electrical or optical properties.…”

Identification of current transport mechanism in Al2O3 thin films for memory applications

“…The Schottky barrier height, / B obtained from the above fit is 1.35 ± 0.25 eV, which is close to the desired value. Also interesting to note is that this value is higher compared to the value (0.78 eV) reported for Al 2 O 3 in literature for a thickness range for 100 nm (Mikhaelashvili et al 1998). It is most possible that the PDA at a high temperature has increased the bandgap and band offsets of Al 2 O 3 , resulting in an increase in barrier height, thus reducing the leakage current (Wellekens et al 2007;Cimpoiasu et al 2004).…”

Effect of La doping on structural and electrical properties of Bi2Ti2O7thin films

“…Polycrystalline thin films of composition Bi 2 Ti 2 O 7 have high permittivity and low leakage current density [7]. High permittivity dielectrics are widely investigated as alternative gate insulating layers in advanced MOS (metaloxide-semiconductor) transistors [8][9][10][11]. Consequently, Bi 2 Ti 2 O 7 is considered to be a promising alternate material in advanced MOS transistors.…”