Influence of temperature on Al/p-CuInAlSe2 thin-film Schottky diodes

Abstract

Al/p-CuInAlSe2 Schottky diodes were fabricated using the optimized thin layers of CuInAlSe2 semiconductor. These diodes were used to study their temperature-dependent current–voltage (I–V) and capacitance–voltage (C–V) analysis over a wide range of 233–353 K. Based on these measurements, diode parameters such as ideality factor (η), barrier height (ϕbo) and series resistance (Rs) were determined from the downward curvature of I–V characteristics using Cheung and Cheung method. The extracted parameters were found to be strongly temperature dependent; ϕbo increases, while η and Rs decrease with increasing temperature. This behavior of ϕbo and η with change in temperature has been explained on the basis of barrier inhomogeneities over the MS interface by assuming a Gaussian distribution (GD) of the ϕbo at the interface. GD of barrier height (BH) was confirmed from apparent BH (ϕap) versus q/2kT plot, and the values of the mean BH and standard deviation (σs) obtained from this plot at zero bias were found to be 1.02 and 0.14 eV, respectively. Also, a modified \(\ln \left( {J_{\text{s}} /T^{2} } \right) - q^{2} \sigma_{\text{s}}^{2} /2k^{2} T^{2}\) versus q/kT plot for Al/p-CuInAlSe2 Schottky diodes according to the GD gives ϕbo and Richardson constant (A**) as 1.01 eV and 26 Acm−2 K−2, respectively. The Richardson constant value of 26 Acm−2 K−2 is very close to the theoretical value of 30 Acm−2 K−2. The discrepancy between BHs obtained from I–V and C–V measurements has also been interpreted.