摘要
The crystallographic tilt in GaN layers grown by epitaxial lateral overgrowth (ELO) onsapphire (0001) substrates was investigated by using double crystal X-ray diffraction (DC-XRD). Itwas found that ELO GaN stripes bent towards the SiNx mask in the direction perpendicular toseeding lines. Each side of GaN (0002) peak in DC-XRD rocking curves was a broad peak relatedwith the crystallographic tilt. This broad peak split into two peaks (denoted as A and B), and peak Bdisappeared gradually when the mask began to be removed by selective etching. Only narrowpeak A remained when the SiNx mask was removed completely. A model based on these resultshas been developed to show that there are two factors responsible for the crystallographic tilt: Oneis the non-uniformity elastic deformation caused by the interphase force between the ELO GaNlayer and the SiNx mask. The other is the plastic deformation, which is attributed to the change ofthe threading dislocations (TDs) from vertical in the window regions to the lateral in the regionsover the mask.
The crystallographic tilt in GaN layers grown by epitaxial lateral overgrowth (ELO) on sapphire (0001) substrates was investigated by using double crystal X-ray diffraction (DC-XRD). It was found that ELO GaN stripes bent towards the SiNx mask in the direction perpendicular to seeding lines. Each side of GaN (0002) peak in DC-XRD rocking curves was a broad peak related with the crystallographic tilt. This broad peak split into two peaks (denoted as A and B), and peak B disappeared gradually when the mask began to be removed by selective etching. Only narrow peak A remained when the SiNx mask was removed completely. A model based on these results has been developed to show that there are two factors responsible for the crystallographic tilt: One is the non-uniformity elastic deformation caused by the interphase force between the ELO GaN layer and the SiNx mask. The other is the plastic deformation, which is attributed to the change of the threading dislocations (TDs)—from vertical in the window regions to the lateral in the regions over the mask.
基金
This work was supported by the National Natural Science Foundation of China (Grant No. 69825107), NSFC-RGC Joint Program (Grant Nos. NSFC5001161953 and N_HKU028/00).
