Deep levels in InxGa1-xAsyP1-ygrown on (100) GaAs by LPE

The deep level transient spectroscopy (DLTS) technique is applied to a nominally undoped quaternary alloy InxGa1-xAsyP1-y lattice matched to (100) GaAs substrate. Only one electron trap with an activation energy of 0.40-0.43 eV below the bottom of the conduction band is detected in the composition range 0<or=y<or=0.41. This is attributed to an anion vacancy (or a group V ion). It is observed that as the bias pulse duration w is increased, the DLTS peak shifts toward low temperatures, its activation energy is decreased, and the electron capture cross-section becomes small. This can be explained by an anion vacancy surrounded by randomly distributed cations (group III ions of In and Ga). The DLTS peak is broadened by the increase of y, which suggests that the immiscibility among the constituent atoms has a strong effect on their distribution.