Thin film device and its fabrication method

Abstract

The invention provides a thin film device where ionic crystals are epitaxially grown on a Si single crystal substrate through a proper buffer layer, and its for fabrication method. A ZnS layer is first deposited on a Si single crystal substrate. Ionic crystal thin films (an n-GaN layer, a GaN layer, and a p-GaN layer) are deposited thereon. The ZnS thin film is an oriented film excellent in crystallinity and has excellent surface flatness. When ZnS can be once epitaxially grown on the Si single crystal substrate, the ionic crystal thin films can be easily epitaxially grown subsequently. Therefore, ZnS is formed to be a buffer layer, whereby even ionic crystals having differences in lattice constants from Si can be easily epitaxially grown in an epitaxial thin film with few lattice defects on the Si single crystal substrate. The characteristics of a thin film device utilizing it can be enhanced.

1 . (canceled)  
   
   
       2 . The thin film device according to  claim 1 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       3 . The thin film device according to  claim 1 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       4 . The thin film device according to  claim 1 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       5 . A thin film device comprising: 
 a buffer layer comprised of a zinc sulfide layer deposited on a silicon single crystal substrate by epitaxial growth; and    two kinds or more of compound thin films having ionic bonds deposited on the zinc sulfide layer.    
   
   
       6 . The thin film device according to  claim 5 , wherein a metal nitride thin film is used as the compound thin films.  
   
   
       7 . The thin film device according to  claim 5 , wherein a metal oxide thin film is used as the compound thin films.  
   
   
       8 . The thin film device according to  claim 5 , wherein a metal sulfide thin film is used as the compound thin films.  
   
   
       9 . A thin film device comprising: 
 a buffer layer comprised of a zinc sulfide layer and a zinc oxide layer deposited on a silicon single crystal substrate by epitaxial growth; and    a compound thin film having ionic bonds deposited on the buffer layer by epitaxial growth.    
   
   
       10 . The thin film device according to  claim 9 , wherein the compound thin film is a thin film formed by laminating two kinds or more of compound thin films having ionic bonds.  
   
   
       11 . The thin film device according to  claim 9 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       12 . The thin film device according to  claim 9 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       13 . The thin film device according to  claim 9 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       14 . A thin film device comprising: 
 a buffer layer comprised of a zinc sulfide layer and a strontium titanate layer deposited on a silicon single crystal substrate by epitaxial growth; and    a compound thin film having ionic bonds deposited on the buffer layer by epitaxial growth.    
   
   
       15 . The thin film device according to  claim 14 , wherein the compound thin film is a thin film formed by laminating two kinds or more of compound thin films having ionic bonds.  
   
   
       16 . The thin film device according to  claim 14 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       17 . The thin film device according to  claim 14 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       18 . The thin film device according to  claim 14 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       19 . A thin film device comprising: 
 a buffer layer comprised of a zinc sulfide layer and a platinum group layer sequentially deposited on a silicon single crystal substrate by epitaxial growth; and    a compound thin film having ionic bonds deposited on the buffer layer by epitaxial growth.    
   
   
       20 . The thin film device according to  claim 19 , wherein a metal of platinum groups is any one of rhodium, iridium, palladium, and platinum, or an alloy of these, depositing a single layer film thereof or a plurality of layers of thin films.  
   
   
       21 . The thin film device according to  claim 19 , wherein the compound thin film is a thin film formed by laminating two kinds or more of compound thin films having ionic bonds.  
   
   
       22 . The thin film device according to  claim 19 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       23 . The thin film device according to  claim 19 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       24 . The thin film device according to  claim 19 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       25 . A thin film device comprising: 
 a buffer layer comprised of a zinc sulfide layer, a zinc oxide layer, and a platinum group layer sequentially deposited on a silicon single crystal substrate by epitaxial growth; and    a compound thin film having ionic bonds deposited on the buffer layer by epitaxial growth.    
   
   
       26 . The thin film device according to  claim 25 , wherein a metal of platinum groups is any one of rhodium, iridium, palladium, and platinum, or an alloy of these, depositing a single layer film thereof or a plurality of layers of thin films.  
   
   
       27 . The thin film device according to  claim 25 , wherein the compound thin film is a thin film formed by laminating two kinds or more of compound thin films having ionic bonds.  
   
   
       28 . The thin film device according to  claim 25 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       29 . The thin film device according to  claim 25 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       30 . The thin film device according to  claim 25 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       31 . A method for fabricating a thin film device comprising: 
 feeding zinc sulfide in a molecular state onto a silicon single crystal substrate to epitaxially grow zinc sulfide on the substrate under a reduced pressure; and    epitaxially growing a compound thin film having ionic bonds thereon.    
   
   
       32 . The method for fabricating the thin film device according to  claim 31 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       33 . The method for fabricating the thin film device according to  claim 31 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       34 . The method for fabricating the thin film device according to  claim 31 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       35 . A method for fabricating a thin film device comprising: 
 feeding zinc sulfide in a molecular state onto a silicon single crystal substrate to epitaxially grow zinc sulfide on the substrate under a reduced pressure; and    epitaxially growing sequentially two kinds or more of compound thin films having ionic bonds thereon.    
   
   
       36 . The method for fabricating the thin film device according to  claim 35 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       37 . The method for fabricating the thin film device according to  claim 35 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       38 . The method for fabricating the thin film device according to  claim 35 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       39 . A method for fabricating a thin film device comprising: 
 epitaxially growing zinc sulfide on a silicon single crystal substrate;    epitaxially growing zinc oxide thereon; and    further epitaxially growing a compound thin film having ionic bonds thereon.    
   
   
       40 . The method for fabricating the thin film device according to  claim 39 , wherein zinc sulfide in a molecular state is fed onto the silicon single crystal substrate under a reduced pressure, whereby zinc sulfide is epitaxially grown on the substrate.  
   
   
       41 . The method for fabricating the thin film device according to  claim 39 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       42 . The method for fabricating the thin film device according to  claim 39 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       43 . The method for fabricating the thin film device according to  claim 39 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       44 . A method for fabricating a thin film device comprising: 
 epitaxially growing zinc sulfide on a silicon single crystal substrate;    epitaxially growing strontium titanate thereon; and    further epitaxially growing a compound thin film having ionic bonds thereon.    
   
   
       45 . The method for fabricating the thin film device according to  claim 44 , wherein zinc sulfide in a molecular state is fed onto the silicon single crystal substrate under a reduced pressure, whereby zinc sulfide is epitaxially grown on the substrate.  
   
   
       46 . The method for fabricating the thin film device according to  claim 44 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       47 . The method for fabricating the thin film device according to  claim 44 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       48 . The method for fabricating the thin film device according to  claim 44 , wherein a metal sulfide thin film is used as the compound thin film.  
   
   
       49 . A method for fabricating a thin film device comprising: 
 epitaxially growing zinc sulfide on a silicon single crystal substrate;    epitaxially growing a platinum group thereon; and    further epitaxially growing a compound thin film having ionic bonds thereon.    
   
   
       50 . The method for fabricating the thin film device according to  claim 49 , wherein zinc sulfide in a molecular state is fed onto the silicon single crystal substrate under a reduced pressure, whereby zinc sulfide is epitaxially grown on the substrate.  
   
   
       51 . The method for fabricating the thin film device according to  claim 49 , wherein a metal nitride thin film is used as the compound thin film.  
   
   
       52 . The method for fabricating the thin film device according to  claim 49 , wherein a metal oxide thin film is used as the compound thin film.  
   
   
       53 . The method for fabricating the thin film device according to  claim 49 , wherein a metal sulfide thin film is used as the compound thin film.