Bandlike and localized states of extended defects in n-type In0.53Ga0.47As

Abstract

In 0.53 Ga 0.47 As p + n diodes with different densities of extended defects have been analyzed by detailed structural and electrical characterization. The defects have been introduced during Metal-Organic Vapor Phase Epitaxy (MOVPE) growth by using a lattice-mismatched layer on a semi-insulating InP or GaAs substrate. The residual strain and indium content in the n-type In 0.53 Ga 0.47 As layer have been determined by high-resolution X-ray diffraction, showing nearly zero strain and a fixed indium ratio of 0.53. The deep levels in the layer have been characterized by Deep Level Transient Spectroscopy. The mean value of electron traps at 0.17 ± 0.03 eV below the conduction band minimum E C is assigned to the "localized" states of α 60°misfit dislocations; another broad electron trap with mean activation energies between E C − 0.17 ± 0.01 and 0.39 ± 0.04 eV, is identified as threading dislocation segments with "band-like" states. A high variation of the pre-exponential factor K T by 7 orders of magnitude is found for the latter when changing the filling pulse time, which can be explained by the coexistence of acceptor-like and donor-like states in the core of split dislocations in III-V materials. Furthermore, two hole traps at E V + 0.42 ± 0.01 and E V + 0.26 ± 0.13 eV are related to the double acceptor of the Ga(In) vacancy (V Ga/In 3-/2-) and 60°β misfit dislocations, respectively. Finally, the dislocation climbing mechanism and the evolution of the antisite defects As Ga/In are discussed for n-type In 0.53 Ga 0.47 As.

Observation of the Stacking Faults in In0.53Ga0.47As by Electron Channeling Contrast Imaging

“…In the AFM image, many cross‐hatch lines in the [1‐10] direction originating from α MD can be observed in Figure b–d, and additional defects called micro‐crack (dark grooves in [110] direction in Figure c) are recognized in sample P_In40 only. A detailed interpretation can be found in the study by Hsu et al Although the AFM image fairly reveals the defects by morphology variation, by selecting a relative flat region (the square region in Figure d,e), ECCI could further distinguish more defects from dark or bright contrast straight lines in the [1‐10] direction. These kinds of defects that are neither visualized by AFM nor originating from surface roughness have the same origin as α MD, as discussed later.…”

“…These eight systems are listed in Table . Because the gliding mobility of α MD is much larger than for β MD, α MD tends to elongate faster and then blocks β MD, resulting in a preferred [1‐10] anisotropic morphology and asymmetric relaxation originating from α MD in the tensile In x Ga 1− x As/InP system . If performing ECCI on this preferred α MD (between Figure a,b and Figure 3d,e), it should be always visible, because never equals zero for both g = (220) and g = (2‐20) diffraction directions.…”

“…The tendency of contrast for these two defects can be explained by the invisibility criterion . For an overlayer under tensile stress, there are eight primary slip systems that produce MDs with a positive edge component for (001) crystalline directions . These eight systems are listed in Table .…”

“…Three blanket samples, having the same structure but different Indium content of 150 nm p+ In 0.53 Ga 0.47 As (≈10 18 cm −3 )/850 nm n− In 0.53 Ga 0.47 As (≈2 × 10 16 cm −3 )/550 nm n+ In x Ga 1− x As (≈2 × 10 19 cm −3 )/2″ semi‐insulating (SI) InP substrate (001), were grown by metalorganic vapor phase epitaxy (MOVPE) . The growth‐induced extended defects were generated intentionally by the lattice mismatch of the n+ layer with different indium contents x and propagated to the surface of p+ In 0.53 Ga 0.47 As of interest that was analyzed by ECCI.…”

“…Except these Ga‐rich samples, an In‐rich sample with same p+/n−/n+/SI‐InP layout but with indium component 76% in full layer was marked as P_all_In76. The extended defect density of the n+ layer and n− layer (up to 750 nm from the junction toward the n+ layer) was estimated by the rocking curve of high‐resolution X‐ray diffraction (HRXRD) and deep level transient spectroscopy (DLTS), which showed a range between 1 × 10 5 and 1 × 10 8 cm −2 .…”