Recently, there are several articles discussed how using ohmic and schottky contact mechanism to form sensors and how to increase the sensitivity and efficiency. Most of them are focus on the single material detection; but there are few articles used one material to functionalize the other material for intensifying the detection ability. In this study, we used two different materials (Germanium and Tin dioxide nanowire) to fabricate Ge/SnO2 nano-heterojunction device (GSNHD) for light and gas detection. For light detection, the broadband light can be detected due to the heterojunction interface. That is because the band continue formed by the heterojunction formation. So the GSNHD can detect different wavelengths light by operating the device tuning voltage. In gas sensing, due to the device scale-down, the Joule heating effect can be enlarged to enhance the oxygen and carbon monoxide adsorption and desorption capability. Worth to mention, the sensing ability of GSNHD is different for different gas environments by tuning voltage. From above experiment, GSNHD shows high sensitivity for environment changing. The ability of broadband light and gas detection can be improved because the band engineering of GSNHD by tuning voltage. In this research work, the multi-capability ability can be proved by using GSNHD.