This paper investigates the differences of wafer-bonded n-(Al0.7Ga0.3)(0.5)In0.5P/n-GaP, n-Ga0.5In0.5P/n-GaP and n-GaP/n-GaP hetero-interfaces. The current-voltage characteristics have been demonstrated to be a result of different wafer cleaning methods. Bonded interfaces were also characterised by scanning electron microscopy and transmission electron micoscopy. In addition, an (AlxGa1-x)(0.5)In0.5P light-emitting diode (LED) was fabricated by wafer direct bonding technique. The luminous intensity of the wafer-bonded (AlxGa1-x)(0.5)In0.5P/GaP LED is about two times brighter than the conventional device with an absorbing GaAs substrate.