Performance of Yb/p-CIGS Schottky Photodiodes at Low Temperatures

The Yb/p-Cu(InxGa<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{{x}-{1}}$ </tex-math></inline-formula>)Se2 (CIGS) Schottky photodiodes were fabricated on Mo-coated glass substrates. Structural and morphological characterizations of the CIGS on the Mo layer were investigated. The current-voltage (I–V) characteristics of the produced devices were performed for dark and solar light (100 mW/cm2) in the temperature range of 40–300 K. The activation energy (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{a}$ </tex-math></inline-formula>) was found to be 0.645 eV from the temperature dependence of the open circuit voltage. It was determined that this value is very close to half of the bandgap of CIGS thin films (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{g}$ </tex-math></inline-formula>, 1.35 eV for this study). The responsivity and detectivity values were calculated for a wide temperature range. The responsivity value decreased and the detectivity value increased with the decrease in temperature. The highest responsivity value was found as 14.3 mA/W at 280 K. The highest detectivity value was calculated as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${4.97} \times {10}^{{9}}$ </tex-math></inline-formula> Jones at 60 K. The suitability of the produced devices for photodetector applications at low temperatures has been investigated.