High electron mobility transistor including asymmetrical carrier supply

Abstract

A field effect transistor includes a semi-insulating semiconductor substrate; a buffer layer disposed on the substrate and having a high resistance; a first semiconductor layer disposed on the buffer layer and having a relatively high concentration of a dopant impurity; a second semiconductor layer disposed on the first semiconductor layer and having a relatively low concentration of a dopant impurity; a third semiconductor layer disposed on the second semiconductor layer and having a relatively high concentration of a dopant impurity; a fourth semiconductor layer disposed on the third semiconductor layer; and a gate electrode, a source electrode, and a drain electrode disposed on the fourth semiconductor layer wherein the electron affinity of the second semiconductor layer is larger than that of the first and third semiconductor layers, and the difference between the electron affinities of the first and second semiconductor layers proximate their junction is larger than the difference between the electron affinities of the second and third semiconductor layers proximate their junction. The linearity of an output signal with respect to an input signal is improved so that the field effect transistor has improved distortion characteristics and reduced noise on adjacent lines in frequency multiplexed communication.