First observation of the EL2 lattice defect in indium gallium arsenide grown by molecular-beam epitaxy

We have used majority-carrier deep-level transient spectroscopy (DLTS) and photocapacitance measurements in a study of lattice defects present in 1.5-μm-thick layers of n-type ${\mathrm{In}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As, 0.045≤x≤0.18, grown by molecular-beam epitaxy (MBE) on n-type GaAs substrates. Each composition shows in the DLTS data an electron trap whose electron parameters agree with those known for the EL2 defect in InGaAs grown by vapor-phase epitaxy, and also the photocapacitance quenching that is characteristic of EL2 traps. Our results demonstrate for the first time that the EL2 defect can be formed in InGaAs during MBE growth, and we deduce its likely mode of formation.