[19a-311-1~12] 17.3 Layered materials

▲ [19a-311-5] Fabrication of germanium-MoS₂ heterostructure for broadband photoresponsive device application

〇(D)Rakesh Dayaram Mahyavanshi¹, Masaki Tanemura¹, Golap Kalita¹ (1.NIT, Nagoya)

Keywords:Layered heterostructure, Photoresponse

Heterojunction of two dimensional (2D) and bulk semiconductors has opened up new possibilities for next-generation photonic and nanoelectronic device applications. The combination of germanium (Ge) with transition metal dichalcogenides (TMDCs) can emanate new possibilities in the field of optoelectronic devices. In this prospect, we demonstrate the fabrication of a Ge/MoS₂ heterostructure and observed photoresponsivity for wide wavelength range with a photovoltaic action. The MoS₂ layer grown by chemical vapor deposition (CVD) was used as a substrate to deposit the Ge thin film by thermal evaporation. The synthesized MoS₂ layer and Ge/MoS₂ heterostructure was analyzed by optical microscope, scanning electron microscope (SEM), Raman and X-ray photoelectron analysis. Current density-voltage (J-V) characteristics of the device was measured with a two probe system. The optical microscope and SEM images of the Ge and MoS₂ heterostructure. A thin interface was formed in-between the CVD grown MoS₂ and Ge film, considering the atomically smooth surface of MoS₂ layers. J-V characteristics of the Au/Ge/MoS₂/Al device for dark condition presenting the formation of a diode. The Ge/MoS₂ heterojunction showed a photovoltaic action with an open circuit voltage (V_oc) of 0.185 V and short circuit current density (J_sc) of 0.028 mA/cm² under illumination of light. The spectral response showed photoresponsivity for wide wavelength range (wavelength 350-1100 nm) signifying the possibility of developing self-powered broadband photoresponsive device.