Deep level defects in n-type GaAs 1Àx Bi x having 0 < x < 0.012 and GaAs grown by molecular beam epitaxy (MBE) at substrate temperatures between 300 and 400 C have been investigated by Deep Level Capacitance Spectroscopy. Incorporating Bi suppresses the formation of an electron trap with activation energy 0.40 eV, thus reducing the total trap concentration in dilute GaAsBi layers by more than a factor of 20 compared to GaAs grown under the same conditions. We find that the dominant traps in dilute GaAsBi layers are defect complexes involving As Ga , as expected for MBE growth at these temperatures. V

Metal-oxide-semiconductor (MOS) interfaces on n-type 4H and 6H-SiC annealed in nitric oxide (NO) for various times were electrically characterized by high-frequency capacitance-voltage and deep-level-transient spectroscopy (DLTS) measurements. Different types of traps were distinguished by DLTS based on the energy-resolved DLTS spectra and comparing DLTS spectra from the two polytypes. Oxide traps, found at much higher densities in the larger bandgap 4H-SiC, are reduced by NO annealing, and their capture behavior is analytically modeled with a tunneling-dependent capture rate. An interface trap distribution is found in 6H-SiC MOS centered at 0.5 eV below the conduction band. Near interface traps in the SiC within 0.1 eV below the conduction band edge, detected at equal concentrations in both polytypes, are not passivated by NO annealing.

We proposed a surface control process for suppressing the tunneling leakage of Schottky gates on AlGaN/GaN heterostructures. For the recovery of nitrogen-vacancy-related defects and reduction in the amount of oxygen impurities at the AlGaN surface, the process consisted of nitrogen radical treatment, the deposition of an ultrathin Al layer, UHV annealing and finally the removal of the Al layer. Ni/Au Schottky gates fabricated on processed AlGaN surfaces showed pronounced reduction in leakage current and a clear temperature dependence of I-V characteristics, indicating the effective suppression of tunneling leakage in current transport through AlGaN Schottky interfaces.

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Engineered or 'virtual' substrates are of interest to extend the range of epitaxially-grown semiconductor heterostructures available for device applications. To this end, elastically strain-relaxed square features up to 30 μm in size and having an in-plane lattice constant as much as 0.49% larger than the lattice constant of GaAs were fabricated from MOCVD-grown GaAs/In 0.08 Ga 0.92 As/GaAs heterostructures by the in-place bonding method, using either AlAs or Al 0.7 Ga 0.3 As as the sacrificial layer. TEM images show that the solution-bonded interface is flat with a network of sessile edge dislocations that accommodates the different in-plane lattice constants of the feature and the GaAs substrate and a small rotation of the bonded features. Micro-Raman spectroscopy, which has a spatial resolution of ∼1 μm, was shown to be useful for characterizing lattice mismatch strain 0.0023, i.e. with an order of magnitude lower sensitivity than high-resolution XRD.