A Temperature Sensor Based on Al/p-Si/CuCdO₂/Al Diode for Low Temperature Applications

Abstract

CuCdO₂ delafossite oxide film as an interface layer was coated by sol–gel spin coating on p-Si substrate, and thus an Al/p-Si/CuCdO₂/Al diode was fabricated. Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) was used to obtain an image of the CuCdO₂ oxide film. The temperature-dependent behavior of the diode was studied by current–voltage (I–V) and capacitance/conductance–voltage (C/G–V) measurements over the 100–400 K temperature range. It is observed that the ideality factor (n) decreases and zero-bias barrier height (Φ_b0) increases with an increase in temperature. This abnormal behavior of n and Φ_b0 is attributed to barrier inhomogeneities by assuming Gaussian distribution (GD) at the metal–semiconductor interface. For each temperature, the barrier height values obtained from both the conventional I–V and Norde method show good agreement with each other. The I–V–T characteristics have shown the GD, giving a mean barrier height (${\bar{\Phi }}_{b0}$) of 1.04 eV and a standard deviation (σ_s) of 0.12 V. A modified Richardson plot of [ln(I₀/T²) − q²σ ²_s /2k²T² versus q/kT] yields ${\bar{\Phi }}_{b0}$ and A* as 1.06 eV and 31.21 A cm⁻² K⁻² (indicating an agreement with the theoretical value of 32 A cm⁻² K⁻²), showing the promise of CuCdO₂/Si as temperature sensing with a Schottky junction. In addition, C–V and G–V measurements show that the C value decreases and the G value increases as the frequency increases, depending on a continuous distribution of interface states. Also, the capacitance and the conductance values decrease with increasing temperature. The results suggest that Al/p-Si/CuCdO₂/Al diode can be used for temperature sensing applications.