Fast and high photoresponsivity gallium telluride/hafnium selenide van der Waals heterostructure photodiode

Abstract

Transition metal dichalcogenide (TMD) material-based van der Waals (vdW) heterostructures have gained huge attention due to their superior capabilities and multiple functionalities in electronics and optoelectronic devices. In this work, a gallium telluride/hafnium selenide (GaTe/HfSe₂) vdW heterostructure with excellent ohmic contacts is studied. A high gate-modulated rectification ratio (RR) of 6.3 × 10⁵ is attained. Furthermore, the photovoltaic measurement is performed under the illumination of laser light of a wavelength of 532 nm and various powers (20–100 μW). Its rise and decay times (18 μs & 24 μs) are superior among those of various reported vdW heterostructures. The photoresponsivity of GaTe/HfSe₂ is enhanced significantly up to with an external quantum efficiency (EQE = 54%) as compared to those of the various reported vdW heterostructures. Such TMD based heterostructure devices would improve the energy harvesting needs along with the multifunctional logic operations.