| 摘要 |
PURPOSE:To allow obtaining high mutual conductances and low noise indexes even in the high frequency characteristic in a microwave band, by continuously varying the electron affinity of the part contacted with a substrate of the buffer layer. CONSTITUTION:There exists a high resistant Ga1-xAlAs layer 22 wherein the ratio of Al composition is varied continuously 0 to 0.3 on the high resitant GaAs substrate 21. A high resistant Ga1-xAlxAs layer 23, an N type Ga1-x AlxAs layer 24 and a GaAs operating layer 25 having the fixed ratio of composition are formed thereon. When a FET is manufactured by using the crystal of such a structure, not only in DC characteristic the improvement of the mutual conductance, the decrease of the output conductance and the improvement of the withstand voltage can be obtained, but also in the high frequency characteristic in a microwave band, high mutual conductances and low noise indexes can be obtained. |
