FIELD EFFECT TRANSISTOR

摘要

The present invention provides a field effect transistor both exhibiting an excellent performance at high voltage operation as well as a high frequency characteristic. In the present invention, a field effect transistor comprises a layer structure made of compound semiconductor (111) provided on a semiconductor substrate (110) made of GaAs or InP, as an operation layer, and employs a first field plate electrode (116) and a second field plate electrode (118); the second field plate electrode (118) comprises a shielding part (119) located in the region between the first field plate electrode (116) and a drain electrode (114), and serving to shield the first field plate electrode (116) from the drain electrode (114). In particular, when, in the cross sectional view in the gate length direction, the length in the gate length direction of an overlap region, in which the second field plate electrode (118) overlaps the upper part of a structure composed of the first field plate electrode (116) and a gate electrode (113), is designated as Lol, and the gate length is designated as Lg, the relation expressed as 0 ‰ Lol/Lg ‰ 1 holds.