Chemical vapor deposition of chalcogenide materials

Abstract

A chemical vapor deposition (CVD) process for preparing electrical and optical chalcogenide materials. In a preferred embodiment, the instant CVD-deposited materials exhibit one or more of the following properties: electrical switching, accumulation, setting, reversible multistate behavior, resetting, cognitive functionality, and reversible amorphous-crystalline transformations. In one embodiment, a multilayer structure, including at least one layer containing a chalcogen element, is deposited by CVD and subjected to post-deposition application of energy to produce a chalcogenide material having properties in accordance with the instant invention. In another embodiment, a single layer chalcogenide material having properties in accordance with the instant invention is formed from a CVD deposition process including three or more deposition precursors, at least one of which is a chalcogen element precursor. Preferred materials are those that include the chalcogen Te along with Ge and/or Sb.

1 . A method for forming a chalcogenide material comprising the steps of: 
 Providing a substrate;    Placing said substrate in a deposition chamber;    Delivering one or more deposition precursors to said deposition chamber, said deposition precursors being delivered in vapor phase form, at least one of said deposition precursors comprising a chalcogen element; said deposition precursors reacting to form a solid phase thin film on said substrate, said thin film comprising said chalcogen element, said thin film having a threshold voltage;    Wherein said thin film switches from a resistive state to a conductive state upon applying said threshold voltage to said thin film.    
     
     
         2 . The method of  claim 1 , wherein said one or more deposition precursors includes at least two deposition precursors.  
     
     
         3 . The method of  claim 1 , wherein said one or more deposition precursors includes at least three deposition precursors.  
     
     
         4 . The method of  claim 1 , wherein each of said one or more deposition precursors provides at least one element to said thin film during said reaction.  
     
     
         5 . The method of  claim 1 , wherein said thin film comprises at least 2 elements.  
     
     
         6 . The method of  claim 1 , wherein said thin film comprises at least 3 elements.  
     
     
         7 . The method of  claim 1 , wherein said chalcogen element is Te.  
     
     
         8 . The method of  claim 1 , wherein said thin film further comprises Ge.  
     
     
         9 . The method of  claim 1 , wherein said thin film further comprises Sb.  
     
     
         10 . The method of  claim 1 , wherein said thin film comprises Te and Ge.  
     
     
         11 . The method of  claim 1 , wherein said thin film comprises Te, Sb, and Ge.  
     
     
         12 . The method of  claim 1 , wherein said thin film comprises GeTe.  
     
     
         13 . The method of  claim 1 , wherein said thin film comprises Ge 2 Sb 2 Te 5 .  
     
     
         14 . The method of  claim 1 , wherein said thin film returns to said resistive state when said threshold voltage is removed.  
     
     
         15 . The method of  claim 1 , wherein said substrate is in motion during said thin film formation step.  
     
     
         16 . The method of  claim 15 , wherein said moving substrate is a continuous web substrate.  
     
     
         17 . A method for forming a chalcogenide material comprising the steps of: 
 Providing a substrate;    Placing said substrate in a deposition chamber;    Delivering one or more deposition precursors to said deposition chamber, said deposition precursors being delivered in vapor phase form, at least one of said deposition precursors comprising a chalcogen element; said deposition precursors reacting to form a solid phase thin film on said substrate, said thin film comprising said chalcogen element, said thin film having a plurality of states, said thin film being transformable among said states upon application of electrical energy, said states including a plurality of states having distinguishable resistances;    Wherein said plurality of states includes states whose resistances differ by at least a factor of two.    
     
     
         18 . The method of  claim 17 , wherein said plurality of states includes states whose resistances differ by at least a factor of four.  
     
     
         19 . The method of  claim 17 , wherein said plurality of states includes states whose resistances differ by at least a factor of eight.  
     
     
         20 . The method of  claim 17 , wherein said plurality of states includes at least three states.  
     
     
         21 . The method of  claim 17 , wherein said plurality of states includes at least four states.  
     
     
         22 . The method of  claim 17 , wherein said one or more deposition precursors includes at least two deposition precursors.  
     
     
         23 . The method of  claim 17 , wherein said one or more deposition precursors includes at least three deposition precursors.  
     
     
         24 . The method of  claim 17 , wherein each of said one or more deposition precursors provides at least one element to said thin film during said reaction.  
     
     
         25 . The method of  claim 17 , wherein said thin film comprises at least 2 elements.  
     
     
         26 . The method of  claim 17 , wherein said thin film comprises at least 3 elements.  
     
     
         27 . The method of  claim 17 , wherein said chalcogen element is Te.  
     
     
         28 . The method of  claim 17 , wherein said thin film further comprises Ge.  
     
     
         29 . The method of  claim 17 , wherein said thin film further comprises Sb.  
     
     
         30 . The method of  claim 17 , wherein said thin film comprises Te and Ge.  
     
     
         31 . The method of  claim 17 , wherein said thin film comprises Te, Sb, and Ge.  
     
     
         32 . The method of  claim 17 , wherein said thin film comprises GeTe.  
     
     
         33 . The method of  claim 17 , wherein said thin film comprises Ge 2 Sb 2 Te 5 .  
     
     
         34 . A method for forming an electrical switching material comprising the steps of: 
 Providing a substrate;    Depositing a first layer on said substrate;    Depositing a second layer on said first layer to form a penultimate multilayer structure;    Applying energy to said multilayer structure, said energy transforming said penultimate multilayer structure into an ultimate multilayer structure, said ultimate multilayer structure having a threshold voltage;    Wherein said ultimate multilayer structure switches from a resistive state to a conductive state upon applying said threshold voltage to said ultimate multilayer structure.    
     
     
         35 . The method of  claim 34 , wherein application of a voltage to said penultimate multilayer structure does not induce switching from a resistive state to a conductive state.  
     
     
         36 . The method of  claim 34 , wherein said energy is applied in the form of electrical energy.  
     
     
         37 . The method of  claim 34 , wherein at least one of said deposition steps is a chemical vapor deposition step.  
     
     
         38 . The method of  claim 34 , wherein said first layer or said second layer comprises a chalcogen element.  
     
     
         39 . A method for forming a chalcogenide material comprising the steps of: 
 Providing a substrate;    Placing said substrate in a deposition chamber;    Delivering one or more deposition precursors to said deposition chamber, said deposition precursors being delivered in vapor phase form, at least one of said deposition precursors comprising a chalcogen element; said deposition precursors reacting to form a solid phase thin film on said substrate, said thin film comprising said chalcogen element, said thin film comprising one or more additional elements;    Wherein said one or more additional elements does not include Zn, Cd, Hg or Mg.    
     
     
         40 . The method of  claim 39 , wherein said one or more additional elements includes at least two elements.  
     
     
         41 . The method of  claim 39 , wherein said chalcogen element is Se or Te.  
     
     
         42 . The method of  claim 39 , wherein said one or more additional elements include Ge.