Production method for light emitting element

Abstract

In a first invention, a p-type Mg x Zn 1-x O-type layer is grown based on a metal organic vapor-phase epitaxy process by supplying organometallic gases which serves as a metal source, an oxygen component source gas and a p-type dopant gas into a reaction vessel. During and/or after completion of the growth of the p-type Mg x Zn 1-x O-type layer, the Mg x Zn 1-x O-type thereof is annealed in an oxygen-containing atmosphere. This is successful in forming the layer of p-type oxide in a highly reproducible and stable manner for use in light emitting device having the layer of p-type oxide of Zn and Mg. In a second invention, a semiconductor layer which composes the light emitting layer portion is grown by introducing source gases in a reaction vessel having the substrate housed therein, and by depositing a semiconductor material produced by chemical reactions of the source gas on the main surface of the substrate. A vapor-phase epitaxy process of the semiconductor layer is proceed while irradiating ultraviolet light to the main surface of the substrate and the source gases. This is successful in sharply enhancing reaction efficiency of the source gases when the semiconductor layer for composing the light emitting layer portion is formed by a vapor-phase epitaxy process, and in readily obtaining the semiconductor layer having only a less amount of crystal defects. In a third invention, a buffer layer having at least an Mg a Zn 1-a O-type oxide layer on the contact side with the light emitting layer portion is grown on the substrate, and the light emitting layer portion is grown on the buffer layer. The buffer layer is oriented so as to align the c-axis thereof to the thickness-wise direction, and is obtained by forming a metal monoatomic layer on the substrate based on the atomic layer epitaxy, and then by growing residual oxygen atom layers and the metal atom layers. This is successful in obtaining the light emitting portion with an excellent quality. In a fourth invention, a ZnO-base semiconductor active layer included in a double heterostructured, light emitting layer portion is formed using a ZnO-base semiconductor mainly composed of ZnO containing Se or Te, so as to introduce Se or Te, the elements in the same Group with oxygen, into oxygen deficiency sites in the ZnO crystal possibly produced during the formation process of the active layer, to thereby improve crystallinity of the active layer. Introduction of Se or Te shifts the emission wavelength obtainable from the active layer towards longer wavelength regions as compared with the active layer composed of ZnO having a band gap energy causative of shorter wavelength light than blue light. This is contributive to realization of blue-light emitting devices.

1 - 19 . (canceled)  
   
   
       20 . A light emitting device having a light emitting layer portion composed of an Mg a Zn 1-a O-type (where, 0≦a≦1)-oxide and formed on a substrate, and having a buffer layer formed between the substrate and the light emitting layer portion, the buffer layer having at least an Mg a Zn 1-a O-type oxide layer on the contact side with the light emitting layer portion; 
 the Mg a Zn 1-a O-type oxide layer has wurtzite crystal structure in which metal atom layers and oxygen atom layers are alternatively stacked in the direction of the c-axis; and    the buffer layer has the c-axis of the wurtzite crystal structure oriented to the thickness-wise direction, has one metal atom layer as a metal monoatomic layer formed in contact with the substrate, and has the residual oxygen atom layers and the metal atom layers alternatively stacked successive to the metal monoatomic layer.    
   
   
       21 . A light emitting device having a double heterostructured light emitting layer portion which comprises an active layer and cladding layers, wherein the active layer is composed of a Group II-VI compound semiconductor containing Zn as a Group II element, and containing O together with Se or Te as a Group VI element, and the cladding layers are composed of Mg x Zn 1-x O-type (where, 0≦x≦1) oxide.  
   
   
       22 . The light emitting device as claimed in  claim 21 , wherein the active layer has a multi-layered structure in which sub-layers composed of ZnSe or ZnTe are inserted in a main layer composed of ZnO so as to be distributed over the thickness-wise direction.  
   
   
       23 . The light emitting device as claimed in  claim 22 , wherein the sub-layer has a width not larger than that of a unimolecular layer of the active layer.  
   
   
       24 . The light emitting device as claimed in  claim 21 , wherein the cladding layers are composed of ZnO.