For the first time, this work presents a novel combination of gallium arsenide phosphide (GaAsP) and indium gallium arsenide (InGaAs) as drain/channel and source materials, respectively, of tunnel field-effect transistor (TFET) for high-performance ultra-low-power applications. With this combination, the ON-state current of the proposed device is improved ten times as compared with GaAs–Ge TFET; however, the ambipolar current remains equal to the OFF-state current. It also exhibits a very low threshold voltage (half in amount) as compared with GaAs–Ge TFET. Apart from these, GaAsP–InGaAs TFET shows huge reduction in the subthreshold slope for better switching operation.