| 摘要 |
PURPOSE:To obtain the titled device of high performance having good characteristics wherein the hetero interface two-dimensional accumulated state of high mobility electrodes is maintained by a method wherein the second semiconductor layer doped with n type of electron affinities both smaller than that of the first semiconductor layer serving as the channel layer and the third semiconductor layer of non-doped high purity are provided in contact with the first one. CONSTITUTION:In the structure having two hetero interfaces wherein the GaAs channel layer 2 is sandwiched between AlGaAs layers of electron affinities smaller than that of GaAs, the channel layer 2 exists between the AlGaAs layer 6 doped with an n type impurity and the AlGaAs layer 51 of non-doped high purity. Thereby, the electrons exist in a quantum-mechanical potential well composed of the conduction bands of the AlGaAs layers 6 and 51 and the GaAs layer 2 and behave as two dimensional electron gas always quantized in an operated state, thus enabling to obtain good conduction characteristics. When serving as the channel, the thickness of the GaAs layer 2 is suitable in 50- 100Angstrom , since such a quantizing level density that at least current flows is necessary as the lower limit, and no generation of the characteristic deterioration due to the effect of current path stretch is necessary as the upper limit. |
