Direct Evidence for the DX Center Being a Substitutional Donor in AlGaAs Alloy System

An experimental result that the DX center appears in GaAs:Si and GaAsd:Sn under hydrostatic pressure of about 30 kbars has been obtained for the first time. This indicates clearly that the DX center in the AlGaAs alloy system is due to a substitutional donor itself (not a complex referred to as “DX”). The change in nature from the the shallow donor to the deep DX center is discussed based on the complex multivalley conduction band structure of GaAs under various pressures and of AlGaAs with various compositions.