| 摘要 |
PROBLEM TO BE SOLVED: To provide a III-group nitride semiconductor device in which a stress caused by a substrate and by a change in different compositions of Alx Gay In1-x-y N is small and in which a crack is not generated. SOLUTION: In a III-group nitride semiconductor device, a buffer layer 2 which is composed of AlN or of low-temperature-grown GaN and a contact layer 3 which is composed of GaN are laminated on a substrate 1s, and layers 4 to 7 which are composed of III-group nitrides expressed by at least Alx Gay In1-x-y (where 0<=x, y and 0<=x+y<=1) are formed on them. In the III- group nitride semiconductor element, a thermal-stress relaxation layer T which is composed of a III-group nitride by raising a substrate temperature is interposed between the buffer layer 2 and the contact layer 3. Alternatively, a lattice- mismatching relaxation layer which is composed of Alx1 Gay1 In1-x1-y1 N (where 0<=x1, y1, x1<=x and y1<=y) is interposed between the contact layer 3 and the layer T composed of the III-group nitride. In addition, it is preferable that the substrate is formed of a germanium single crystal whose substrate face is a (111) plane. |
