| 摘要 |
PURPOSE:To obtain a device characterized by a high speed and a large current, by providing semiconductor layers having large carrier affinity at the upper and lower sides of a quantum-well shaped potential structure, which supplies carriers, forming two-dimensional carrier gas in the vicinity of each heterojunction interface, and increasing surface concentration. CONSTITUTION:On semi-insulating GaAs, non-added GaAs 2, a quantum well structure 3, non-added GaAs 4 and N-type GaAs 5 are epitaxially grown. The quantum well structure 3 comprises non-added AlAs barriers 3a and 3c with a thickness of 1.5nm, a GaAs well 3b with a thickness of 1nm and 3d. The 3d is provided at the center of the well 3b. In the 3d, Si is added by about 3X10<12>/cm<2>. In this quantum well structure, the energy level of carriers in the layer 3 is enhanced. The surface concentration of the two-dimensional carrier gas in the vicinity of each heterojunction interface is largely increased. Since the two upper and lower layers are formed in the close proximity, the effect is multiplied. The increasing effect of the surface concentration is more effective for electrons than for holes. The effect is conspicuous when the thickness of the well 3 is 3nm or less. |
