Patent ID: 8212252

Claim:
A light-emitting device having a light-emitting element comprising first and second electrodes and a light-emitting layer existing between the first and second electrodes, and a field effect transistor for driving the light-emitting element, wherein an active layer of the field effect transistor comprises an amorphous oxide of a compound having (a) a composition when in crystalline state represented by In 2−x M3 x O 3 (Zn 1−y M2 y O) m , wherein M2 is Mg or Ca; M3 is B, Al, Ga or Y; 0≦x≦2; 0≦y≦1; and m is zero or a natural number less than 6, or a mixture of said compounds; (b) an electron carrier concentration of greater than 10 12 /cm 3 and lesser than 10 18 /cm 3 wherein a current between a drain terminal and a source terminal of the field effect transistor when no gate voltage is applied is less than 10 microamperes; and (c) oxygen defect density decreased by treatment in an atmosphere including oxygen at a predetermined pressure during or after formation of the active layer of the amorphous oxide.