GaN based LEDs are grown on sapphire by MBE using NH3. The n- and p-type doping levels are 4x10(18) and 3x10(17) cm(-3), respectively. LEDs turn on at 3V, and the forward voltage is 3.7V at 20mA. The electroluminescence peaks at 390 nm.
GaN based LEDs grown by molecular beam epitaxy