Thin-film transistor, method of producing thin-film transistor, electronic circuit, display, and electronic device

Abstract

Aspects of the invention can provide a thin-film transistor having good transistor characteristics and operable with a low driving voltage, a method of producing such a thin-film transistor, a high-reliability electronic circuit, a display, and an electronic device. In an exemplary thin-film transistor according to the invention, a gate electrode can be formed on a substrate via an underlying layer, and a gate insulating layer can be formed on the substrate such that the gate electrode is covered with the gate insulating layer. A source electrode and a drain electrode are formed on the gate insulating layer such that they are separated from each other by a gap formed just above the gate electrode. An organic semiconductor layer can be formed thereon such that the electrodes are covered with the organic semiconductor layer. A region between the electrodes of the organic semiconductor layer functions as a channel region. A protective layer can be arranged on the organic semiconductor layer. This thin-film transistor is characterized in that the organic semiconductor layer is formed after the gate insulating layer is formed, and the gate insulating layer has the capability of causing the organic semiconductor layer to be aligned.

1 . A thin-film transistor, comprising: 
 an organic semiconductor layer including a channel region;    a source region and a drain region formed such that the channel region is arranged between the source region and the drain region;    a gate electrode corresponding to the channel region; and    a gate insulating layer disposed between the gate electrode and the organic semiconductor layer and having an alignment surface facing the organic semiconductor layer, the alignment surface aligning the organic semiconductor layer.    
     
     
         2 . The thin-film transistor according to  claim 1 , 
 the alignment surface being formed by aligning the gate insulating layer in a particular direction; and    the organic semiconductor layer being aligned in the particular direction.    
     
     
         3 . The thin-film transistor according to  claim 1 , 
 the alignment surface having a plurality of grooves formed in a particular direction; and    the organic semiconductor layer being aligned in the particular direction.    
     
     
         4 . The thin-film transistor according to  claim 2 , the particular direction being a direction from one of the source region and the drain region to another one via the channel region.  
     
     
         5 . The thin-film transistor according to  claim 1 , the gate insulating layer being formed such that at least a part on a side facing the organic semiconductor layer is formed of an organic material including mainly a polyimide resin.  
     
     
         6 . The thin-film transistor according to  claim 5 , the gate insulating layer including a layer formed mainly of an inorganic material on a side opposite to the organic semiconductor layer.  
     
     
         7 . The thin-film transistor according to  claim 5 , the polyimide resin being in the form of diallyl ketone.  
     
     
         8 . The thin-film transistor according to  claim 1 , the organic semiconductor layer being formed mainly of an organic polymer semiconductor material.  
     
     
         9 . The thin-film transistor according to  claim 1 , the source region and the drain region each being formed mainly of an electrically conductive polymer material.  
     
     
         10 . An electronic circuit including the thin-film transistor according to  claim 1 .  
     
     
         11 . A display including the electronic circuit according to  claim 10 .  
     
     
         12 . An electronic device including a power supply and the display according to  claim 11 .  
     
     
         13 . A method of producing a thin-film transistor, comprising: 
 forming a gate electrode;    forming a gate insulating layer on the gate electrode;    forming an organic semiconductor layer including a channel region on the gate insulating layer; and    forming a source region and a drain region such that the channel region is arranged between the source region and the drain region,    the forming the organic semiconductor layer including aligning at least a part on a side facing the gate insulating layer of the organic semiconductor layer.    
     
     
         14 . The method of producing a thin-film transistor according to  claim 13 , further comprising performing an alignment treatment on a surface facing the organic semiconductor layer of the gate insulating layer, 
 after the performing, the forming the source region and the drain region being performed such that the source region and the drain region are spaced apart from each other along a direction in which a surface of the gate insulating layer is aligned.    
     
     
         15 . The method of producing a thin-film transistor according to  claim 14 , the alignment treatment being performed by rubbing or optical alignment process.  
     
     
         16 . The method of producing a thin-film transistor according to  claim 13 , further comprising performing an alignment treatment at least on a surface facing the organic semiconductor layer of the gate insulating layer, after the forming the source region and the drain region.  
     
     
         17 . The method of producing a thin-film transistor according to  claim 16 , the alignment treatment being performed by optical alignment process.  
     
     
         18 . A method of producing a thin-film transistor according to  claim 13 , in the forming the gate insulating layer, a first layer including mainly an inorganic material being formed and then a second layer including mainly an organic material being formed on the first layer.  
     
     
         19 . A method of producing a thin-film transistor according to  claim 13 , in the forming the organic semiconductor layer, an organic semiconductor material being heated to a temperature higher than a temperature at which the organic semiconductor material changes into a liquid crystal phase, and then the organic semiconductor material being cooled.