| 摘要 |
PURPOSE:To deter gallium in a channel region from diffusing in an aluminum gate and prevent a fluctuation in a threshold voltage by mixing a small amount of gallium in aluminum constituting a gate electrode in advance. CONSTITUTION:An approximately 3,000Angstrom thick n-type GaAs active layer 2 with an impurity density ND of the order of 5.0X10<17>cm<-3> is grown to be formed on a semi-insulative GaAs substrate 1 by means of a CVD method. Gold- germanium and gold are sequentially vapor-deposited on the active layer 2 to be alloyed and AuGe/Au source/drain electrodes 3a and 3b are formed. A recess 4 is formed in a prescribed region between the source/drain electrodes 3a and 3b by a recess etching with a hydrofluoric acid etchant, leaving the remaining bottom wall of the layer 2 with such a thickness that an enhancement type can be obtained. A gate electrode 5 constituted by an Al alloy containing 1% Ga in weight is formed on the recess 4 through vapor deposition and lift-off processes.
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