Structure for fabricating high electron mobility transistors utilizing the formation of complaint substrates

Abstract

High quality epitaxial layers of monocrystalline materials can be grown overlying monocrystalline substrates such as large silicon wafers by forming a compliant substrate for growing the monocrystalline layers. An accommodating buffer layer comprises a layer of monocrystalline oxide spaced apart from a silicon wafer by an amorphous interface layer of silicon oxide. The amorphous interface layer dissipates strain and permits the growth of a high quality monocrystalline oxide accommodating buffer layer. The accommodating buffer layer is lattice matched to both the underlying silicon wafer and the overlying monocrystalline material layer. Any lattice mismatch between the accommodating buffer layer and the underlying silicon substrate is taken care of by the amorphous interface layer. Once such a structure is built, a high electron mobility transistor (HEMT) or a heterojunction bipolar transistor (HBT) can be constructed on the structure. A HEMT or HBT of the above structure can then be used in a switch or in an amplifier.