| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a nitride semiconductor structure having a flat plane or a hetero interface at an atomic level. <P>SOLUTION: The nitride semiconductor substrate 101 is GaN having (11-20) plane as a principal orientation plane and density of a threading dislocation 104 including a helical component is 1×10<SP POS="POST">5</SP>cm<SP POS="POST">-2</SP>. A masking material 102 (a silicon oxide thin film with 100 nm thickness) having a plurality of apertures 103 (a square having 20 microns sides) is formed on the substrate. In the apertures, n type GaN layers 106a, undoped AlN layers 106b, undoped GaN layers 106c, undoped AlN layers 106d, and n type GaN layers 106e are sequentially formed. By examining the relationship between the density of threading dislocations 104 and the area of the apertures 103 under various conditions, it is found that when the density of threading dislocations is N cm<SP POS="POST">-2</SP>, at least one interface of the nitride semiconductor multi-layer thin film formed in each aperture 103 is made flat provided that the area of each aperture 103 is equal to or less than 1/N cm<SP POS="POST">2</SP>. <P>COPYRIGHT: (C)2012,JPO&INPIT |
