| 摘要 |
PROBLEM TO BE SOLVED: To prevent a low resistance layer from being formed in a surface of a silicon board by setting a sheet resistance of a silicon board surface part at a specified amount or more. SOLUTION: As for a silicon board 1, a high resistance silicon board whose impurity concentration is about 1×10<12> cm<-3> and sheet resistance is 40 kΩ/(square) is used. A low resistance layer containing As is not in a surface of the silicon board 1 and its sheet resistance is 2000Ω/(square) or more. A buffer layer 2 is provided on the silicon board 1. Since a sheet resistance of a surface part of the silicon board 1 is made 2000Ω/(square) or more in this way, good characteristic is realized without flow of leakage current through a surface part of the silicon board 1 when a compound semiconductor layer is made an active layer of a field effect transistor. |
