GaN and InGaN alloys were grown on c-plane sapphire substrates by molecular beam epitaxy using NH3. This allows realizing light emitting diodes (LEDs) based on InGaN/GaN single heterostructures. The forward voltage is 3.6 V at 20 mA. The room temperature electroluminescence exhibits a strong emission at 405 nm. The I-V characteristics were studied as a function of the temperature. A tunneling process in the transport mechanism is observed as for metal-organic chemical vapor deposition grown LEDs.