Contact structures for n-type diamond

Abstract

Electronic devices and more particularly diamond-based electronic devices and corresponding contact structures are disclosed. Electrical contact structures to diamond layers, including n-type, phosphorus doped single-crystal diamond are disclosed. In particular, electrical contact structures are formed through an arrangement of one or more nanostructured carbon layers with high nitrogen incorporation that are provided between metal contacts and n-type diamond layers in diamond-based electronic devices. Nanostructured carbon layers may be configured to mitigate reduced phosphorus incorporation in n-type diamond layers, thereby providing low specific contact resistances for corresponding devices. Diamond p-i-n diodes for direct electron emission applications are also disclosed that include electrical contact structures with nanostructured carbon layers.

What is claimed is: 
     
         1 . A method for fabricating an electronic device, the method comprising:
 forming a diamond layer;   depositing a nanostructured carbon layer on the diamond layer, the nanostructured carbon layer comprising an average grain size in a range from 10 nm to 1000 nm; and   depositing a metal contact layer on the nanostructured carbon layer, wherein the metal contact layer and the nanostructured carbon layer form a contact structure in conductive electrical communication with the diamond layer.   
     
     
         2 . The method of  claim 1 , further comprising cleaning a surface of the diamond layer before said depositing of the nanostructured carbon layer. 
     
     
         3 . The method of  claim 1 , wherein said depositing of the nanostructured carbon layer comprises a plasma-enhanced chemical vapor deposition (PECVD) process. 
     
     
         4 . The method of  claim 3 , wherein the nanostructured carbon layer is doped with nitrogen, and a gas mixture used to deposit the nanostructured carbon layer during the PECVD process comprises at least 50% nitrogen. 
     
     
         5 . The method of  claim 4 , wherein the gas mixture comprises at least 70% nitrogen. 
     
     
         6 . The method of  claim 5 , wherein the gas mixture further comprises argon. 
     
     
         7 . The method of  claim 5 , wherein the gas mixture comprises at least 10% hydrocarbon. 
     
     
         8 . The method of  claim 7 , wherein the hydrocarbon comprises methane. 
     
     
         9 . The method of  claim 1 , wherein the diamond layer comprises n-type conductivity and the nanostructured carbon layer comprises n-type conductivity. 
     
     
         10 . The method of  claim 1 , wherein the nanostructured carbon layer comprises n-type conductivity, and a nitrogen concentration of the nanostructured carbon layer is in a range from about 4.5×10 20  cm −3  to about 5.5×10 20  cm −3 . 
     
     
         11 . The method of  claim 1 , wherein the nanostructured carbon layer comprises n-type conductivity, and a nitrogen concentration of the nanostructured carbon layer is in a range from about 1×10 19  cm −3  to about 5.5×10 20  cm −3 . 
     
     
         12 . A method for fabricating a diode, the method comprising:
 providing a p-type diamond layer;   depositing an intrinsic diamond layer on the p-type diamond layer;   depositing an n-type diamond layer on the intrinsic diamond layer;   depositing a nanostructured carbon layer that is doped with nitrogen on the n-type diamond layer; and   depositing a metal contact layer on the nanostructured carbon layer, wherein the metal contact layer and the nanostructured carbon layer form a contact structure in conductive electrical communication with the n-type diamond layer.   
     
     
         13 . The method of  claim 12 , further comprising forming a mesa that includes the metal contact layer, the nanostructured carbon layer, the n-type diamond layer, and a portion of the intrinsic diamond layer. 
     
     
         14 . The method of  claim 12 , wherein the nanostructured carbon layer comprises an average grain size in a range from 10 nm to 1000 nm. 
     
     
         15 . The method of  claim 12 , wherein the nanostructured carbon layer comprises n-type conductivity, and a nitrogen concentration of the nanostructured carbon layer is in a range from about 4.5×10 20  cm −3  to about 5.5×10 20  cm −3 . 
     
     
         16 . The method of  claim 12 , wherein the nanostructured carbon layer comprises n-type conductivity, and a nitrogen concentration of the nanostructured carbon layer is in a range from about 1×10 19  cm −3  to about 5.5×10 20  cm −3 . 
     
     
         17 . The method of  claim 12 , wherein said depositing of the nanostructured carbon layer comprises a plasma-enhanced chemical vapor deposition (PECVD) process. 
     
     
         18 . The method of  claim 17 , wherein a gas mixture used to deposit the nanostructured carbon layer during the PECVD process comprises at least 50% nitrogen. 
     
     
         19 . The method of  claim 17 , wherein the gas mixture comprises at least 70% nitrogen. 
     
     
         20 . The method of  claim 19 , wherein the gas mixture further comprises argon and a hydrocarbon.