The silicon doping of GaAs grown by metalorganic chemical vapor deposition using a silane source has been investigated. The amphoteric property of the Si dopant is demonstrated for the first time. It is found that the doping characteristics are strongly temperature dependent. At the growth temperature higher than 600 °C and the arsine to trimethylgallium mole ratio (AsH3/TMG) around 217, the conduction isntype and the carrier concentration increases as the temperature increases. On the other hand, when the growth temperature is lower than 600 °C, the carrier concentration increases as the temperature decreases and the conduction becomesptype at 400–450 °C. In addition, when the AsH3/TMG mole ratio is below 50, the Si‐doped GaAs layers also becomeptype. The GaAs light‐emitting diode is thus successfully fabricated using a single silicon dopant.