Abstract
The electrical properties of Au/Ti/HfO2/n-GaAs metal/insulating layer/semiconductor (MIS) contact structures were analyzed in detail by the help of capacitance–voltage (C–V) and conductance–voltage (G–V) measurements in the temperature range of 60–320 K. The HfO2 thin-film layer was obtained by atomic layer deposition technique (ALD). The main electrical parameters such as ideality factor (n) and barrier height (ΦB0) were determined for Au/Ti/n-GaAs and Au/Ti/HfO2/n-GaAs diodes using current–voltage (I–V) measurement at 300 K. The values of these parameters are 1.07 and 0.77 eV for the reference (Au/Ti/n-GaAs) diode and 1.30 and 0.94 eV for the Au/Ti/HfO2/n-GaAs MIS diode, respectively. An interfacial charge density value of \({Q}_{ss}\)= 4.14 × 1012 Ccm−2 for the MIS diode was calculated from the barrier height difference of \(\Delta\Phi =0.94-0.77=0.17 \mathrm{V}\). Depending on these results, the temperature-dependent C–V and G–V plots of the device were also investigated. The series resistance (Rs), phase angle, the interface state density (Dit), the real impedance (Z′) and imaginary impedance (Z″) were evaluated using admittance measurements. The C and G values increased, whereas (Z″) and Z decreased with increasing voltage at each temperature. An intersection point being independent of temperature in the G–V curves appeared at forward-bias side (≈1.4 V); after this intersection point of the G–V plot, the G values decreased with increasing temperature at a given voltage. The intersection points in total \(Z\) versus V curves appeared at forward-bias side (≈1.7 V). The Nyquist spectra were recorded for the MIS structure showing single semicircular arcs with different diameters depending on temperature.
Highlights
Thin-film technology has been widely used in the production of electronic devices from past to present and characterization of variety of them derived from traditional metal– semiconductor (MS) junction with Schottky barrier formation between metal and semiconductor [1, 2]
The main electrical parameters such as Bo and n for the Au/Ti/HfO2/n-gallium arsenide (GaAs) metal/insulating layer/semiconductor (MIS) structure fabricated by the atomic layer deposition technique (ALD) method and reference Au/Ti/n-GaAs diode was determined 0.94 eV and 1.30 and 0.77 eV and 1.07 from I-V curves at room temperature, respectively
The interfacial HfO2 thin layer increased these values for the MIS structure and lowered leakage current
Summary
Thin-film technology has been widely used in the production of electronic devices from past to present and characterization of variety of them derived from traditional metal– semiconductor (MS) junction with Schottky barrier formation between metal and semiconductor [1, 2]. Schottky diodes (SDs) are the simplest MS contact devices [8,9,10,11,12,13] and so that the understanding of which has great technological importance in the electronics. At this point, since gallium arsenide (GaAs) is one of the most important materials for low-power and high-speed devices, a full understanding of the nature of the electrical characteristics of GaAs based SDs is essential for its application. Biber et al [12], Kahveci et al [11] and Karabulut [13] have obtained an approximate value of zero-bias barrier height (ΦB0) as around 0.76 eV at 300 K for Au/Ti/n-GaAs MS diode
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