| 摘要 |
<p>PURPOSE: To prevent leakage current and back gate effect by isolating a channel from a substrate perfectly through an air gap. CONSTITUTION: An undoped GaAs layer 22 includes an air gap 23 having rectangular cross-section above an insulation layer 21. An AlGaAs:Se layer 24 serves as an electron supply layer and 2DEG (two-dimensional electron gas) is formed on the interface to an underlying undoped GaAs layer 22. The AlGaAs:Se layer 24 suppresses ionization of DX center causing reduction of drain current strongly at the time of low temperature operation thus enhancing stabilization of the characteristic of an HEMT. At the time of forming an undoped GaAs layer 22, the air gap 23 formed as expected electrically isolates the current channel perfectly from a semiconductor substrate 20. According to the structure, back gate effect can be prevented by preventing formation of unnecessary depletion region between the current channel and the substrate 20.</p> |
