Comparison of deep level spectra of MBE- and MOCVD-grown InGaAsN

摘要

Deep level transient spectroscopy (DLTS) studies of both p-type (uid) and n-type (Si-doped), lattice-matched, 1.05 eV bandgap InGaAsN grown by molecular-beam epitaxy (MBE) are reported, and the results are compared to previous measurements of similar materials grown by metal-organic chemical-vapor deposition (MOCVD). In MBE-grown p-type InGaAsN, two majority-carrier hole traps were observed: H3' (0.37 eV) and H4' (0.51 eV), and no evidence was found for the presence of minority-carrier electron traps. These two traps appear to be similar to two levels, H3 (0.48 eV) and H4 (0.5 eV), previously characterized in MOCVD-grown InGaAsN. In MBE-grown n-type InGaAsN, we observed a shallow distribution of electron levels, El' (0 < E_A < 0.35 eV), as well as a deep electron trap E4' (0.56 eV) and a deep hole trap H5' (0.71 eV). El' appears to be coincident with a superposition of two levels observed in MOCVD-grown InGaAsN, a shallow distribution termed El (0 < E_A < 0.20 eV) and a discrete (though broadened) level E3 (0.34 eV). Further, E4' appears to be similar in character to a level observed in MOCVD-grown material, E4 (0.82 eV), although a disparity in activation energy exists. This disparity may be due to a temperature-dependent capture cross-section for one or both levels, a possibility that is currently under investigation. In contrast, H5' appears to have no analogue in MOCVD-grown material and thus may be unique to the MBE growth technique.