M. Dąbrowska-Szata

Investigation of deep-level defects in InGaAsN/GaAs 3xQWs structures grown by AP-MOVPE

We have investigated deep-level defects in InGaAsN/GaAs 3xQW structures by means of conventional as well as high-resolution deep level transient spectroscopy (DLTS). The three samples were grown by atmospheric pressure metalorganic vapour phase epitaxy (AP-MOVPE) in different growth temperatures (566°C, 575°C and 585°C). The DLTS measurements revealed four electron traps E1 (0.17-0.24 eV), E2 (0.36-0.38 eV), E3 (0.46-0.49 eV) and E4 (0.81-0.84 eV) and one hole trap H1(0.8 eV) in our structures. The electron trap E1 was associated with N-related complexes while the other electron traps with native defects, usually observed in GaAs-based structures EL6, EL3 and EL2, respectively. Finally, the trap E2 and H1, observed in the structure grown at lowest temperature, were associated with the same trap, which can act as both an electron and hole trap. It was thus concluded that E2/H1 may be a generation-recombination center.

Electrically active defects in SiC Schottky barrier diodes

The electrical properties of deep-level defects in real packaged SiC Schottky barrier rectifiers were studied by deep level transient spectroscopy (DLTS). One deep-level trap with an activation energy in the 0.29–0.30 eV range was revealed to be present in all the tested samples. The electrical characteristics of the trap indicate it is probably attributed to dislocations or to metastable defects, which can be responsible for discrepancies observed in I-V characteristics (see Ref. [2]).

Characterization of deep-level defects in GaNAs/GaAs heterostructures grown by APMOVPE

Abstract Conventional deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS techniques were used to study electrical properties of deep-level defects in dilute GaNAs epitaxial layers grown by atmospheric-pressure metalorganic vapourphase epitaxy (APMOVPE) on the GaAs substrate. Three samples with nitrogen concentrations of 1.2 %, 1.6 % and 2.7 % were investigated. In DLTS and LDLTS spectra of the samples, four predominant electron traps were observed. On the basis of the obtained electrical parameters and previously published results, one of the traps was associated with N-related complex defects, while the other traps with common GaAs-like native defects and impurities, called EL6, EL3 and EL2.

DLTS and PR Studies of Partially Relaxed InGaAs/GaAs Heterostructures Grown by MOVPE

The studies of electrical activity of deep electron traps and the optical response of partially-strain relaxed InxGa1-xAs layers (x=5.5%, 7.7% and 8.6%) grown by metalorganic vapourphase epitaxy (MOVPE) have been performed by means of deep-level transient spectroscopy (DLTS) and photoreflectance (PR). DLTS measurements revealed two electron traps. One of the trap has been attributed to electron states at α-type misfit dislocations. The other trap has been ascribed to the EL2 point defect. The PR spectra at room temperature were measured and analysed. By applying the results of theoretical calculations which include excitonic and strain effects, we were able to estimate the extent of strain relaxation and the values of residual strain in the partially relaxed epitaxial layers.