Thin-film transistor and method for producing same

Abstract

A thin film transistorincludes: a gate electrode, a semiconductor layerdisposed on the gate electrode via a gate insulating layer, a source electrodedisposed on a portion of the semiconductor layervia a first contact layer Cs, and a drain electrodedisposed on another portion via a second contact layer Cd. The first and second contact layers have a multilayer structure including N (where N is an integer equal to or greater than 1) two-layer structures S(n) (where n is an integer not smaller than 1 and not greater than N), each two-layer structure S(n) including a first amorphous silicon layerthat is directly in contact with the source or drain electrode, a second amorphous silicon layer(), and a third amorphous silicon layer() that is directly in contact with an upper face thereof. In each two-layer structure S(n), n type impurity concentrations C2() and C3() of the second amorphous silicon layer and the third amorphous silicon layer and an n type impurity concentration C1 of the first amorphous silicon layer satisfy C2()<C3()<C1 for any given n.