Field-effect transistor including transparent oxide and light-shielding member, and display utilizing the transistor

Abstract

A field-effect transistor includes a substrate, a source electrode, a drain electrode, a gate electrode, a gate-insulating film, and an active layer. The active layer contains an oxide having a transmittance of 70% or more in the wavelength range of 400 to 800 nm. A light-shielding member is provided as a light-shielding structure for the active layer, for example, on the bottom face of the substrate.

1 . A field-effect transistor comprising a substrate, a source electrode, a drain electrode, a gate electrode, a gate-insulating film, and an active layer, wherein 
 the active layer contains an oxide having a transmittance of 70% or more in the wavelength range of 400 to 800 nm; and    a light-shielding structure is provided between the substrate and the active layer or is provided on the surface of the substrate on the side opposite the active layer.    
   
   
       2 . The field-effect transistor according to  claim 1 , wherein the light-shielding structure has a light-shielding property that prevents entry of light from the substrate side toward the active layer.  
   
   
       3 . The field-effect transistor according to  claim 1 , wherein the light-shielding structure has a light-shielding property that prevents entry of light having a wavelength range of 400 to 800 nm.  
   
   
       4 . The field-effect transistor according to  claim 1 , wherein the light-shielding structure has a light-shielding property that prevents entry of at least light or an electromagnetic wave having a wavelength range of 300 to 500 nm.  
   
   
       5 . The field-effect transistor according to  claim 1 , wherein the oxide is an amorphous oxide.  
   
   
       6 . The field-effect transistor according to  claim 1 , wherein the oxide contains at least one of In, Zn, and Sn.  
   
   
       7 . The field-effect transistor according to  claim 1 , wherein the oxide is an amorphous oxide containing at least one of In, Zn, and Ga.  
   
   
       8 . A display comprising a plurality of pixel parts each provided with a field-effect transistor according to  claim 1  and a liquid-crystal layer or a light-emitting layer.  
   
   
       9 . A field-effect transistor comprising a substrate, a source electrode, a drain electrode, a gate electrode, a gate-insulating film, and an active layer, wherein 
 the active layer contains an oxide having a transmittance of 70% or more in the wavelength range of 400 to 800 nm; and    the substrate has a light-shielding property.    
   
   
       10 . The field-effect transistor according to  claim 9 , wherein the substrate has a light-shielding property that prevents entry of light from the substrate side toward the active layer.  
   
   
       11 . The field-effect transistor according to  claim 9 , wherein the substrate has a light-shielding property that prevents entry of light having a wavelength range of 400 to 800 nm.  
   
   
       12 . The field-effect transistor according to  claim 9 , wherein the substrate has a light-shielding property that prevents entry of at least light or an electromagnetic wave having a wavelength range of 300 to 500 nm.  
   
   
       13 . The field-effect transistor according to  claim 9 , wherein the oxide is an amorphous oxide.  
   
   
       14 . The field-effect transistor according to  claim 9 , wherein the oxide contains at least one of In, Zn, and Ga.  
   
   
       15 . The field-effect transistor according to  claim 9 , wherein the oxide is an amorphous oxide containing at least one of In, Zn, and Ga.  
   
   
       16 . A display comprising a plurality of pixel parts each provided with a field-effect transistor according to  claim 9  and a liquid-crystal layer or a light-emitting layer.  
   
   
       17 . A field-effect transistor comprising a substrate, a source electrode, a drain electrode, a gate electrode, a gate-insulating film, an active layer, and a light-shielding structure, wherein 
 the active layer contains an oxide having a transmittance of 70% or more in the wavelength range of 400 to 800 nm; and    the light-shielding structure is provided over the active layer.    
   
   
       18 . The field-effect transistor according to  claim 17 , wherein the light-shielding structure has a light-shielding property that prevents entry of light from the active layer side toward the substrate.  
   
   
       19 . The field-effect transistor according to  claim 17 , wherein the light-shielding structure has a light-shielding property that prevents entry of light at angles of less than 90 degrees to the surface of the substrate toward the active layer.  
   
   
       20 . The field-effect transistor according to  claim 17 , wherein the light-shielding structure overlaps the source electrode and the drain electrode.