| 摘要 |
PURPOSE:To obtain a compound semiconductor substrate whose dislocation density is less by providing undoped semi-insulating epitaxial compound semiconductor substrate on a compound semiconductor substrate having the specified conductivity type and the specified impurity concentration or higher. CONSTITUTION:As the impurity concentration of a compound semiconductor substrate, 5X10<17>cm<-3> or higher is required. For example, the substrate is cut out of an N-type GaAs single crystal having low dislocation density obtained by lifting N-type GaAs wherein a silicon element is added as impurities by 5X10<17>cm<-3> or higher by an LEC method. Thus a substrate 1 for epitaxial growth is obtained. Mirror surface treatment, chemical treatment and the like are performed on the surface of the substrate 1. An undoped semi-insulating GaAs crystal layer 2 is epitaxially grown on the surface. Then, the high-quality compound semiconductor substrate having the low dislocation density with the semi-insulating property being maintained is obtained. As the film thickness (t) of the crystal 2, the minimum thickness required for the active region of an element formed in the crystal layer is necessary. When any of MBE, MOCVD or MOMBE is used for the epitaxial growth of the crystal layer 2, the controllability of the film thickness (t) and the film quality can be improved. |
