Spin semiconductor transistors are well recognised as potential future solutions for a digital high-performance computation and memory. With Intel's announcement of corporate interests in silicon spin qubits for quantum computing, and Google, IBM and other companies making major investments in research and development to build quantum computers, semiconductor spintronic transistors have become object of a strategic economic importance. In this feasibility study, we will develop a doping methodology for gallium nitride using manganese to create contacts for wide-bandgap semiconductor transistors. We will use gallium manganese nitride, a dilute magnetic material with a low, 5% content of manganese to build a prototype of a spin injection contact. Gallium manganese nitride shows a Curie temperature (the temperature at which material loses its permanent magnetic properties) well above a room temperature, can be fabricated using high-quality epitaxial growth, and shows also a large concentration of holes. All these hold great promise for a spin injection and spin control and in a field-effect transistor.