Glide of threading dislocations in (In)AlGaAs on Si induced by carrier recombination: Characteristics, mitigation, and filtering

Abstract

III-V optoelectronics grown epitaxially on Si substrates have large networks of dislocations due to a lattice constant mismatch between the device layers and the substrate. Recombination-enhanced dislocation glide (REDG) allows these dislocations to move and increase in length during device operation, which degrades performance. In this paper, we study REDG dynamics of threading dislocations in situ in (In)AlGaAs double heterostructures grown on Si substrates using scanning electron microscopy cathodoluminescence. The driving force for REDG arises due to coefficient of thermal expansion differences between Si and the III-V layers leading to large residual strains in the films. Tracking of threading dislocations as moving dark spot defects reveals glide characteristics that vary based on the nature of the dislocation. Remarkably, the alloying of a few atom percent of indium using metamorphic structures arrests threading dislocation glide by more than two orders of magnitude. Finally, we present REDG-based filtering as a pathway to reducing the threading dislocation density in select areas, removing a large fraction of the mobile dislocations. Together, these techniques will enable the understanding of dislocation-dislocation and carrier-dislocation interactions that have so far remained elusive during device operation, leading to reliable III-V integrated optoelectronics on silicon.

A Pathway to Thin GaAs Virtual Substrate on On‐Axis Si (001) with Ultralow Threading Dislocation Density

“…It was previously discussed [ 29 ] that the reactions between the TDs in a zinc‐blend crystal maintain a glissile versus sessile ratio of 1:1, and this has also been experimentally observed. [ 38 ] Therefore, the supply of glissile TDs does not quickly run out. Thus, the plateauing of the TDD with respect to the number of cycles is primarily due to work hardening as the misfit dislocations (MDs) at the GaAs/Si interface elongate in each cycle.…”

Defect filtering for thermal expansion induced dislocations in III–V lasers on silicon

“…The indium containing QD layer, however, locally pins the threading dislocation segment where it cuts through (blue box in Figure 1c). [30] The pinning shear, a result of resistive forces imparted by both precipitate-like InAs QDs and alloy fluctuations in the In0.15Ga0.85As QW, inhibits threading-dislocation glide in the QD layer. Thus, only the free threading segment in the GaAs buffer glides and, in doing so, lays down a misfit dislocation segment at the QD layer interface (Figure 1c).…”

Nondestructive characterization of threading dislocations in graded buffer layers of inverted metamorphic solar cells by two-photon excitation spectroscopy

“…39) The 2PPL images discussed above have a spatial resolution that is equivalent to the resolutions provided by EBIC and CL techniques. 40,41) Furthermore, our results indicate that the information of the target layer can be obtained by choosing the appropriate detection wavelength. Note that the 2PPL images were obtained by using a long-pass DM that reflects light with wavelengths below 850 nm.…”