| The alloy InxGa1− xAs1−yN y is a novel semiconductor in which the bandgap may be specified while maintaining lattice-match to GaAs. This work has focused on the deep level transient spectroscopy (DLTS) measurement of 1.05 eV alloys containing 7% indium and 2% nitrogen. In unintentionally doped (uid) p-type material grown by metalorganic chemical vapor deposition (MOCVD), we have detected four hole traps: H1, H2, H3, and H4, located at 0.10, 0.23, 0.48, and ∼0.5 eV above the valence band edge, respectively. All are believed to be due to energy distributions within the semiconductor bandgap. The concentrations of H1, 142, and H4 fell following thermal annealing, and the reduction of H4 correlated with improved bulk electronic properties. Characterization of additional samples showed that deep level concentrations depend on nitrogen content as well as MOCVD precursor gas flow conditions. DLTS measurements of MBE-grown p-type (uid) InGaAsN have detected two deep levels, E3′ and E4′, whose positions are roughly consistent with those of H3 and H4. In n-type MOCVD-grown InGaAsN doped with tin, four electron levels were measured in annealed material: E1, E2, E3, and E4. E1 is a broad distribution (0.2 eV wide) of states below the conduction band edge, whereas E2, E3, and E4 appear to be broadened levels centered at 0.36, 0.34, and 0.40 eV, respectively. E2 was absent in as-grown material, and a hole trap (H6, 0.71 eV) was likewise observed in annealed material only. These two levels, which constitute a recombination-generation center, are believed to be due to a single extended defect resulting from imperfect nucleation of InGaAsN on a GaAs surface. E3 appears to correlate with the use of tin as an n-type dopant. In MBE-grown n-type (Si-doped) InGaAsN, two levels were observed: E1′ and E4′, which are approximately consistent with levels E1 and E4. The positions of E1/E1′ and E4/E4 ′ are roughly coincident with states predicted by an alloy-fluctuation model put forth in the literature to describe the structure of the conduction band of InGaAsN alloys. Finally, a minority-carrier hole trap of unknown origin, H5′, was observed in n-type InGaAsN grown by MBE. |
