Stable amorphous metal oxide semiconductor

Abstract

A thin film semiconductor device has a semiconductor layer including a mixture of an amorphous semiconductor ionic metal oxide and an amorphous insulating covalent metal oxide. A pair of terminals is positioned in communication with the semiconductor layer and define a conductive channel, and a gate terminal is positioned in communication with the conductive channel and further positioned to control conduction of the channel. The invention further includes a method of depositing the mixture including using nitrogen during the deposition process to control the carrier concentration in the resulting semiconductor layer.

1 . A stable amorphous metal oxide material for use as a semiconductor in semiconductor devices, the material comprising a mixture of an amorphous semiconductor ionic metal oxide and an amorphous insulating covalent metal oxide, wherein the amorphous semiconductor ionic metal oxide material has a grain size equal to or smaller than 100 nm. 
     
     
         2 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the amorphous semiconductor ionic metal oxide is in an amount much greater than the amorphous insulating covalent metal oxide. 
     
     
         3 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the amount of amorphous insulating covalent metal oxide is sufficient to prevent the amorphous semiconductor ionic metal oxide from becoming poly crystalline at process temperatures. 
     
     
         4 . A stable amorphous metal oxide material as claimed in  claim 3  wherein the amount of amorphous insulating covalent metal oxide is sufficient to prevent the amorphous semiconductor ionic metal oxide from becoming poly crystalline at process temperatures in a range of approximately 250° C. to approximately 700° C. 
     
     
         5 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the amount of amorphous insulating covalent metal oxide is sufficiently small to allow a continuous network of the amorphous semiconductor ionic metal oxide. 
     
     
         6 . A stable amorphous metal oxide material as claimed in  claim 5  wherein the amount of amorphous semiconductor ionic metal oxide is greater than approximately 17% of the mixture. 
     
     
         7 . A stable amorphous metal oxide material as claimed in  claim 5  wherein the amorphous insulating covalent metal oxide is greater than approximately 5% of the mixture. 
     
     
         8 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the amorphous semiconductor ionic metal oxide includes one of zinc oxide, indium oxide, tin oxide, gallium oxide, cadmium oxide, or combinations thereof. 
     
     
         9 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the amorphous insulating covalent metal oxide includes one of aluminum oxide, silicon oxide, magnesium oxide, beryllium oxide, boron oxide, or combinations thereof. 
     
     
         10 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the mixture at least partially includes the amorphous semiconductor ionic metal oxide (XO) and the amorphous insulating covalent metal oxide (YO) according to the formula XO a YO b , where ‘a’ is the amount of amorphous semiconductor ionic metal oxide in the composite mixture and ‘b’ is the amount of amorphous insulating covalent metal oxide in the composite mixture. 
     
     
         11 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the mixture comprises oxygen atoms bonded to both metal Y and metal X in the form of X—O—Y, wherein metal X forms ionic bond with the oxygen and metal Y forms covalent bond with the oxygen. 
     
     
         12 - 30 . (canceled) 
     
     
         31 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the amorphous insulating covalent metal oxide has a grain size equal to or smaller than 100 nm. 
     
     
         32 . A stable amorphous metal oxide material as claimed in  claim 1  wherein the amorphous semiconductor ionic metal oxide is characterized by an energy gap less than approximately 4 ev in its single phase and the amorphous insulating covalent metal oxide is characterized by an energy gap greater than approximately 6 ev in its single phase.