Elastic surface wave functional device and electronic circuit using the element

摘要

PCT No. PCT/JP96/00339 Sec. 371 Date Jul. 22, 1998 Sec. 102(e) Date Jul. 22, 1998 PCT Filed Feb. 16, 1996 PCT Pub. No. WO96/25792 PCT Pub. Date Aug. 22, 1996A surface acoustic wave functional element is provided that includes a piezoelectric substrate or a multilayer piezoelectric substrate having a large electromechanical coupling coefficient. Semiconductor layers are formed on the piezoelectric substrate. The semiconductor layers include an active layer and a buffer layer. The buffer layer is formed of a structure that has a lattice constant that is the same as or similar to that of the active layer. In addition, input and output electrodes are formed on both sides of the semiconductor layers. The surface acoustic wave functional clement attains a large amplification gain at low voltage, and can be used as part of a transmitting/receiving circuit in a high frequency portion of a mobile communication device.