| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain an MESFET for oscillator driving which does not vary oscillation frequency by specifying the resistivity of a substrate and incorporating a specific amount of chromium as impurities in the substrate. SOLUTION: So that the MESFET can have a stable oscillation waveform, 0.1 to 0.4wf.ppm chromium is added as impurities. In this case, the resistivity of a gallium arsenide substrate is 1.0 to 3.0×108ω/cm. The impurities added to the substrate is not limited to chromium and may be iron. Both chromium and iron have properties of forming a deep acceptor potenitial and are expected to compensate a deep potential represented by a crystal defect. When iron is added as the impurities, the resistivity of the substrate needs to be 1.0-3.0×108Ω.cm so that a forward bias applied to the substrate reduces a current flowing in the substrate. Consequently, stable oscillation characteristics can be obtained.</p> |
