Field effect transistor using amorphous oxide film as channel layer, manufacturing method of field effect transistor using amorphous oxide film as channel layer, and manufacturing method of amorphous oxide film
An amorphous oxide containing hydrogen (or deuterium) is applied to a channel layer of a transistor. Accordingly, a thin film transistor having superior TFT properties can be realized, the superior TFT properties including a small hysteresis, normally OFF operation, a high ON/OFF ratio, a high saturated current, and the like. Furthermore, as a method for manufacturing a channel layer made of an amorphous oxide, film formation is performed in an atmosphere containing a hydrogen gas and an oxygen gas, so that the carrier concentration of the amorphous oxide can be controlled.
1. A field effect transistor comprising:
a channel layer of an amorphous oxide film containing In or Zn,
wherein the amorphous oxide film shows an electron carrier concentration and an electron mobility such that the electron mobility tends to increase as the electron carrier concentration increases,
wherein the amorphous oxide film contains hydrogen or deuterium at a concentration in the range of 10 16 to 10 20 /cm 3 , and
wherein the composition of the amorphous oxide film containing hydrogen or deuterium is represented by the following equation that excludes the hydrogen:
[(Sn 1-x M4 x )O 2 ] a .[(In 1-y M3 y ) 2 O 3 ]b .[Zn 1-z M2 z O] c
where 0≦x≦1, 0≦y≦1, 0≦z<1, 0≦a<1, 0≦b<1, 0≦c<1, and a+b+c=1 hold,
M4 is an element (Si, Ge, or Zr) of Group IV having an atomic number smaller than that of Sn,
M3 is Lu or an element (B, Al, Ga, or Y) of Group III having an atomic number smaller than that of In, and
M2 is an element (Mg or Ca) of Group II having an atomic number smaller than that of Zn.
2. The field effect transistor according to claim 1 ,
wherein the concentration of hydrogen or deuterium contained in the amorphous oxide film is in the range of 10 17 to 10 19 /cm 3 .
3. The field effect transistor according to claim 1 ,
wherein the M3 comprises Ga.
4. A field effect transistor having a channel layer of an amorphous oxide film containing Ga, In and Zn,
wherein the amorphous oxide film shows an electron carrier concentration and an electron mobility such that the electron mobility tends to increase as the electron carrier concentration increases, and
wherein the amorphous oxide film contains hydrogen or deuterium at a concentration in the range of 10 16 to 10 20 /cm 3 .