| 摘要 |
PURPOSE:To increase mutual conductance and operate a device at high speed and in high gains by adequately deciding the concentration of impurities of a region under a gate electrode of a semiconductor layer. CONSTITUTION:The relation ship of the concentration ND' of impurities of a region 2a under a gate electrode 6 of a semiconductor layer 2, the concentration ND of impurities of regions 2b except the region 2a of a section between a region under a source electrode 3 of the semiconductor layer 2 and a region under a drain electrode 4 and the thickness (a) of the semiconductor layer 2 is set to ensure that the concentration ND' of impurities has the relationship of [(2Vp.Lg)/Lgs(Vgs-VT)]<2>. ND<ND'<ND under a condition of Lgs(Vgs-VT)>2Vp.Lg, and has the relationship of [(2Vp.Lg/Lgs(Vgs-VT)]<2>.ND>ND'>ND under a condition of Lgs(Vgs- VT)<2Vp.Lg, and the thickness (a) has the relationship of a=(2epsilon.Vp/q.ND')<1/2>. Where Lgs; a distance between the electrodes of the gate 3 and the source 6, Vgs; voltage between said electrodes, VT; threshold value voltage in the case when a section between said electrodes is not conducted, Vp; pinch-off voltage, Lg; the length of the gate electrode 3, epsilon; a dielectric constant of the semiconductor 2, q; the electric charges of electrons. |
