Photovoltaic Effect in T1InS2-, T1GaSe2- and T1GaS2-based Barrier Structures

A photovoltaic effect is observed in In/T1MeX₂ (T1MeX₂=T1InS₂ or TlGaSe₂ or T1GaS₂) and InSe/T1MeX₂ barrier structures at room temperature. The photovoltaic effect is found to lie at photon energies above the band gap of T1MeX₂ (Eg = 2.4eV, 2.1eV and 2.5eV for T1InS₂, T1GaSe₂ and T1GaS₂, respectively) in In/T1MeX₂-type structures, it lies in between the band gaps of narrow-gap (InSe, Eg = 1.2eV) and wide-gap (T1MeX₂) components in InSe/T1MeX₂-type structures. Remarkably enough, some of the obtained InSe/T1GaSe₂ and InSe/T1InS₂ structures exhibited voltage sensitivity (∼10⁴V/W) comparable to that of commercial Si-photodiode.