Dislocation reduction in non-polar iii-nitride thin films

Abstract

Lateral epitaxial overgrowth of non-polar III-nitride seed layers reduces threading dislocations in the non-polar III-nitride thin films. First, a thin patterned dielectric mask is applied to the seed layer. Second, a selective epitaxial regrowth is performed to achieve a lateral overgrowth based on the patterned mask. Upon regrowth, the non-polar III-nitride films initially grow vertically through openings in the dielectric mask before laterally overgrowing the mask in directions perpendicular to the vertical growth direction. Threading dislocations are reduced in the overgrown regions by (1) the mask blocking the propagation of dislocations vertically into the growing film and (2) the bending of dislocations through the transition from vertical to lateral growth.

What is claimed is: 
     
         1 . A non-polar III-nitride thin film comprising a non-polar III-nitride layer disposed on a pattern mask. 
     
     
         2 . The film of  claim 1 , wherein the pattern mask comprises a blocking region and a window region. 
     
     
         3 . The film of  claim 1 , wherein the pattern mask has a long and narrow stripe pattern. 
     
     
         4 . The film of  claim 1 , wherein the non-polar III-nitride layer comprises an asymmetric growth region. 
     
     
         5 . The film of  claim 4 , wherein the asymmetric growth region comprises facing opposing polarities of growth on a c-plane side wall. 
     
     
         6 . The film of  claim 5 , wherein the opposing polarities are +c-plane and −c-plane. 
     
     
         7 . The film of  claim 5 , wherein the opposing polarities are Ga face and N-face. 
     
     
         8 . The film of  claim 7 , wherein the asymmetric growth region comprises a longer Ga face region than an N face region. 
     
     
         9 . The film of  claim 4 , wherein the non-polar III-nitride layer comprises a threading dislocation parallel to the pattern mask. 
     
     
         10 . The film of  claim 9 , wherein the non-polar III-nitride layer comprises a bent threading dislocation from vertical to lateral with respect to the pattern mask. 
     
     
         11 . The film of  claim 4 , wherein the asymmetric growth region is perpendicular to the pattern mask. 
     
     
         12 . The film of  claim 1 , wherein the non-polar III-nitride layer comprises a symmetric growth region parallel to pattern mask. 
     
     
         13 . The film of  claim 1 , wherein the pattern mask is aligned along a [−1100] direction. 
     
     
         14 . The film of  claim 1 , wherein the pattern mask is aligned along a [0001] direction. 
     
     
         15 . The film of  claim 1 , wherein the pattern mask is aligned between [0001] and [−1100] directions. 
     
     
         16 . The film of  claim 1 , wherein the pattern mask is aligned along a [−1101] direction. 
     
     
         17 . The film of  claim 1 , wherein the non-polar III-nitride layer is a [11-20] a-plane non-polar GaN layer. 
     
     
         18 . The film of  claim 1 , wherein the non-polar III-nitride layer is disposed on a substrate. 
     
     
         19 . The film of  claim 18 , wherein the substrate is r-plane sapphire. 
     
     
         20 . The film of  claim 18 , wherein a seed layer is disposed between the non-polar III-nitride layer and the substrate. 
     
     
         21 . A method for fabricating a non-polar III-nitride thin film comprising depositing a non-polar III-nitride layer on a pattern mask. 
     
     
         22 . A non-polar III-nitride thin film fabricated using the method of  claim 21 .