Ultraviolet Detection Properties of p-Si/n-TiO₂Heterojunction Photodiodes Grown by Electron-Beam Evaporation and Sol–Gel Methods: A Comparative Study

Abstract

This paper reports a comparative study of the ultraviolet (UV) detection properties of n-TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /p-Si heterojunction devices fabricated using two different deposition techniques namely the electron-beam evaporation (EBE) and sol-gel (SG) methods. A systematic study has also been carried out to investigate the structural, electrical, and optical properties of the as deposited TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thin films on p-Si substrates by the EBE and SG methods. The electrical parameters of both the n-TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /p-Si heterojunction photodiodes have been measured and compared under dark and UV illumination conditions. The SG based n-TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /p-Si heterojunction photodiodes are observed with an excellent contrast ratio of ~83911 at -5.2 V bias voltage, which is ~6445 times higher than the EBE-based device. The measured responsivities of the EBE and SG based devices are ~0.69 and ~1.25 A/W at a bias voltage of -10 V (P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">opt</sub> = 650 μW and λ = 365 nm), respectively. Thus, the n-TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /p-Si heterojunction diodes with SG derived TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> films are considered to be a better choice over the EBE-based n-TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /p-Si diodes for UV detection applications.