Mis-il silicon solar cell with passivation layer to induce surface inversion

Abstract

The present invention relates generally to a photovoltaic solar cell device and more particularly, to a structure and method of inducing charge inversion in a silicon substrate by using a highly charged passivation layer on an upper side of the silicon substrate. A positively charged passivation layer comprising hafnium oxide may be formed on an insulating layer covering an upper surface of a p-doped silicon substrate and on a metal contact to induce a strong inversion layer in an upper portion of the p-doped silicon substrate.

What is claimed is: 
     
         1 . A metal-insulator-semiconductor inversion layer (MIS-IL) solar cell structure comprising:
 an insulating layer on an upper surface of a substrate;   an n-type region in an upper portion of the substrate immediately below the insulating layer;   a metal contact on the insulating layer, the insulating layer separates the metal contact from the n-type region in the upper portion of the substrate; and   a positively charged metal oxide layer on an upper surface of the insulating layer and covering the metal contact.   
     
     
         2 . The structure of  claim 1 , wherein a thickness and charge density of the positively charged metal oxide layer is directly proportional to a thickness and charge density of the n-type region in the upper portion of the substrate. 
     
     
         3 . The structure of  claim 1 , wherein the substrate comprises p-doped silicon and the n-type region in the upper portion of the substrate comprises a larger electron concentration than a remainder of the substrate. 
     
     
         4 . The structure of  claim 1 , wherein the metal contact comprises copper, silver, gold, tungsten, aluminum, or alloys thereof. 
     
     
         5 . The structure of  claim 1 , wherein the positively charged metal oxide layer comprises hafnium oxide or lanthanum oxide, and has a thickness ranging from approximately 0.1 nm to approximately 5 nm. 
     
     
         6 . A metal-insulator-semiconductor inversion layer (MIS-IL) solar cell structure comprising:
 an insulating layer on an upper surface of a substrate;   an n-type region in an upper portion of the substrate immediately below the insulating layer;   a metal contact on the insulating layer, the insulating layer separates the metal contact from the n-type region in the upper portion of the substrate;   a positively charged metal oxide layer on an upper surface of the insulating layer and covering the metal contact; and   a silicon nitride layer covering the positively charged metal oxide layer.   
     
     
         7 . The structure of  claim 6 , wherein a thickness and charge density of the positively charged metal oxide layer is directly proportional to a thickness and charge density of the n-type region in the upper portion of the substrate. 
     
     
         8 . The structure of  claim 6 , wherein the substrate comprises p-doped silicon and the n-type region in the upper portion of the substrate comprises a larger electron concentration than a remainder of the substrate. 
     
     
         9 . The structure of  claim 6 , wherein the positively charged metal oxide layer has a thickness ranging from approximately 0.1 nm to approximately 5 nm. 
     
     
         10 . The structure of  claim 6 , the positively charged metal oxide layer comprises hafnium oxide and the metal contact comprises copper, silver, gold, tungsten, aluminum, or alloys thereof. 
     
     
         11 . A metal-insulator-semiconductor inversion layer (MIS-IL) solar cell structure comprising:
 an insulating layer on an upper surface of a substrate;   a metal layer on a bottom surface of the substrate;   an n-type region in an upper portion of the substrate immediately below the insulating layer;   a p+ doped layer in a bottom portion of the substrate immediately above the metal layer;   a metal contact on the insulating layer, the insulating layer separates the metal contact from the n-type region in the upper portion of the substrate;   a positively charged metal oxide layer on an upper surface of the insulating layer and covering the metal contact; and   a silicon nitride layer covering the positively charged metal oxide layer.   
     
     
         12 . The structure of  claim 11 , wherein a thickness and charge density of the positively charged metal oxide layer is directly proportional to a thickness and charge density of the n-type region in the upper portion of the substrate. 
     
     
         13 . The structure of  claim 11 , wherein the insulating layer comprises silicon oxide. 
     
     
         14 . The structure of  claim 11 , wherein the metal layer comprises copper, silver, gold, tungsten, aluminum, or alloys thereof. 
     
     
         15 . The structure of  claim 11 , wherein the n-type region in the upper portion of the substrate comprises a larger electron concentration than a remainder of the substrate. 
     
     
         16 . The structure of  claim 11 , wherein the metal contact comprises copper, silver, gold, tungsten, aluminum, or alloys thereof. 
     
     
         17 . The structure of  claim 11 , wherein the positively charged metal oxide layer comprises hafnium oxide or lanthanum oxide. 
     
     
         18 . The structure of  claim 11 , wherein the positively charged metal oxide layer has a thickness ranging from approximately 0.1 nm to approximately 5 nm. 
     
     
         19 . The structure of  claim 11 , wherein the substrate comprises p-doped silicon. 
     
     
         20 . The structure of  claim 11 , wherein the substrate comprises a silicon-on-insulator substrate or a silicon germanium-on-insulator substrate.