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

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 (eta), barrier height (phi(bo)) and series resistance (R-s) 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; phi(bo) increases, while eta and R-s decrease with increasing temperature. This behavior of phi(bo) and eta 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 phi(bo) at the interface. GD of barrier height (BH) was confirmed from apparent BH (phi(ap)) versus q/2kT plot, and the values of the mean BH and standard deviation (sigma(s)) obtained from this plot at zero bias were found to be 1.02 and 0.14 eV, respectively. Also, a modified ln(J(s)/T-2) - q(2)sigma(2)(s)/2k(2)T(2) versus q/kT plot for Al/p-CuInAlSe2 Schottky diodes according to the GD gives phi(bo) 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.