Columnar crystal containing light emitting element and method of manufacturing the same

Abstract

A method of manufacturing a semiconductor element by forming, on a substrate, columnar crystals of a nitride-base or an oxide-base compound semiconductor, and by using the columnar crystals, wherein on the surface of the substrate, the columnar crystals are grown while ensuring anisotropy in the direction of c-axis, by controlling ratio of supply of Group-III atoms and nitrogen, or Group-II atoms and oxygen atoms, and temperature of crystal growth, so as to suppress crystal growth in the lateral direction on the surface of the substrate.

1 . A method of manufacturing a semiconductor element by forming, on a substrate, columnar crystals of a nitride-base or an oxide-base compound semiconductor, and by using thus-formed columnar crystals,
 wherein on a surface of said substrate, said columnar crystals are grown while ensuring anisotropy in a direction of c-axis, by controlling ratio of supply of Group-III atoms and nitrogen, or Group-II atoms and oxygen atoms, and temperature of crystal growth, so as to suppress crystal growth in a lateral direction on the surface of the substrate.   
     
     
         2 . The method of manufacturing a semiconductor element as claimed in  claim 1 , wherein said ratio of supply of the source atoms and nitrogen or oxygen atom, and the temperature of crystal growth are adjusted with respect to a mode of allowing growth of the columnar crystals while ensuring anisotropy, after the growing while ensuring anisotropy in the direction of c-axis, so as to allow the columnar crystals to grow not only in a longitudinal direction thereof but also isotropically. 
     
     
         3 . The method of manufacturing a semiconductor element as claimed in  claim 1 , wherein at a time of starting the growth of said columnar crystals, dots which serve as nuclei for allowing said columnar crystals to grow on the surface of the substrate are formed according to a predetermined size and to a predetermined distribution density. 
     
     
         4 . The method of manufacturing a semiconductor element as claimed in  claim 1 , wherein said columnar crystals are separated from said substrate, and bonded to another substrate. 
     
     
         5 . The method of manufacturing a semiconductor element as claimed in  claim 1 , wherein gaps between adjacent columnar crystals are filled with an insulating material. 
     
     
         6 . The method of manufacturing a semiconductor element as claimed in  claim 1 , wherein a diameter of said columnar crystals is 50 nm to 100 nm. 
     
     
         7 . The method of manufacturing a semiconductor element as claimed in  claim 3 , wherein the forming of said nucleis for allowing said columnar crystals to grow comprises using a SiO 2  film or a Ti film as a mask and forming holes in the SiO 2  film or in the Ti film where a growth is desired to proceed, so as to make the surface of said substrate exposed therein. 
     
     
         8 . The method of manufacturing a semiconductor element as claimed in  claim 1 , further comprising, in said columnar crystals, forming a device structure having an optical or electronic function. 
     
     
         9 . The method of manufacturing a semiconductor element as claimed in  claim 8 , wherein said device structure having said optical or electronic function is a region formed as an active region expressing a functionality of one of controlling light emission and direction of current flow. 
     
     
         10 . The method of manufacturing a semiconductor element as claimed in  claim 1 ,
 wherein said columnar crystals comprises a light emitting layer,   when said columnar crystals is said nitride-base compound semiconductor, as materials for said columnar crystals and said light emitting layer, InGaN, GaN, AlGaInN, AlGaN, AlN or hetero-structures composed of these materials is employed, and   when said columnar crystals is said oxide-base compound semiconductor, as materials for said columnar crystals and said light emitting layer, ZnO, CdZnO, MgZnO, MgZnCdO or hetero-structures composed of these materials is employed.   
     
     
         11 . The method of manufacturing a semiconductor element as claimed in  claim 1 , comprising at the time of starting the growth of said columnar crystals, forming dots having a diameter of 50 nm to 100 nm as nuclei for allowing said columnar crystals to grow on the surface of the substrate are formed according to a predetermined distribution density. 
     
     
         12 . The method of manufacturing a semiconductor element as claimed in  claim 2 , wherein the allowing the columnar crystals to grow not only in the longitudinal direction thereof but also isotropically comprises making top portions of the columnar crystals in a form of a reverse pyramid, on which a crystal is grown as a continuous film of the compound semiconductor.