Abstract: A semiconductor-containing heterostructure including, from bottom to top, a III-V compound semiconductor buffer layer, a III-V compound semiconductor channel layer, a III-V compound semiconductor barrier layer, and an optional, yet preferred, III-V compound semiconductor cap layer is provided. The barrier layer may be doped, or preferably undoped. The III-V compound semiconductor buffer layer and the III-V compound semiconductor barrier layer are comprised of materials that have a wider band gap than that of the III-V compound semiconductor channel layer. Since wide band gap materials are used for the buffer and barrier layer and a narrow band gap material is used for the channel layer, carriers are confined to the channel layer under certain gate bias range. The inventive heterostructure can be employed as a buried channel structure in a field effect transistor.