| 摘要 |
PURPOSE:To obtain a high electron mobility transistor which has less decrease in electron mobility by sequentially forming an electron run layer of a semiconductor crystal of low impurity density, a buffer layer of semiconductor single crystal of high forbidden band width and low impurity density, and an electron supply layer of semiconductor signal crystal of high impurity density of a semi- insulating substrate. CONSTITUTION:A GaAs single crystal 22 not doped with an impurity is, for example, grown by a MBE process on a semi-insulating GaAs substrate 21, an AlXGa1-XAs layer 23 not doped with an insulator is grown as a buffer layer thereon, an AlXGa1-XAs layer 24 doped with an Si is grown by the MBE process as an electron supply layer thereon, a control electrode 26, a source electrode 27 and a drain electrode 28 are provided, and a high electron mobility transistor is formed. In this case, the molar ratio X of the layer 23 and AlX Ga1-XAs of the layer 24 is continuously varied from X=0.3 to X=0.7 from the hetero boundary to the control electrode 26. |
