Nature, origin and effect of dislocations in epitaxial semiconductor layers

Booker, G. R.; Titchmarsh, J.M.; Fletcher, J.; Darby, D.; Hockly, M.; Al‐Jassim, M. M.

doi:10.1016/0022-0248(78)90470-0

Cited by 68 publications

(16 citation statements)

References 2 publications

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“…The latter mechanism prevails for those defects situated closer to the sidewalls. So-called growth dislocations oriented along [001] ( [19,28]) have not been detected. Mist dislocations at the GaAs/Si interface, caused by the 4.1% lattice mismatch ε = (a f − a s )/a s with a f and a s the lattice constant of the lm and substrate, respectively, have been detected in cross-sectional low magnication TEM images in the two-beam contrast mode (not shown here) and in GPA maps (Fig.…”

Section: Resultsmentioning

confidence: 99%

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A Structural Characterization of GaAs MBE Grown on Si Pillars

Frigeri¹,

Bietti²,

Scaccabarozzi³

et al. 2014

Acta Phys. Pol. A

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Growth on deeply patterned substrates, i.e. on pillars instead of a continuous substrate, is expected to be very promising to get crack free epilayers on wafers without any bowing. We report here on a structural investigation of GaAs MBE deposited on patterned (001) ocut Si, consisting of pillars 8 µm high and 5 to 9 µm wide, to check mostly the behaviour of the threading dislocations. It is found that only very rarely they propagate up to the GaAs top that will serve as active region in devices. Twins were also detected which sometimes reached the topmost part of GaAs. However, as twins have no associated dangling bonds, they should not be electrically active. Rare antiphase boundaries exist at the interface, hence not harmful for device operation.

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Section: Resultsmentioning

confidence: 99%

“…• MDs and 1 for edge MDs [28]. The value of k = 0.5 is due to the fact that only the edge component of a 60…”

Section: Resultsmentioning

confidence: 99%

A Structural Characterization of GaAs MBE Grown on Si Pillars

Frigeri¹,

Bietti²,

Scaccabarozzi³

et al. 2014

Acta Phys. Pol. A

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“…1). [31][32][33][34][35] Misfit dislocations can also be formed via the nucleation of dislocation half-loops at steps or impurities at the growth surface. The half-loop grows into the layer until it intersects and glides along the interface, leaving behind a misfit segment connected by two threading-dislocation segments that terminate on the free surface (Fig.…”

Section: Introductionmentioning

confidence: 99%

Threading and misfit-dislocation motion in molecular-beam epitaxy-grown HgCdTe epilayers

Carmody

Lee

Zandian

et al. 2003

Journal of Elec Materi

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INTRODUCTIONThe performance of long-wave infrared (LWIR) and very long-wave infrared (VLWIR) photovoltaic devices can be degraded by the presence of dislocations in the HgCdTe epitaxial layer. 1-5 Dislocations threading the junction region can theoretically act as tunneling (conductive) pathways, and dislocations in the active layer can also act as trapping and recombination centers that degrade detector performance. [1][2][3][4][5] When dislocations in LWIR and VLWIR HgCdTe focal-plane arrays (FPAs) intersect the diode region, they result in degraded zero-bias impedance (R o A) and an increased diode dark current. Consequently, understanding and controlling the formation and motion of dislocations in the junction region of the diode are of critical concern when fabricating highperformance LWIR and VLWIR detectors.It is well-known that the misfit strain between the substrate and the epitaxial layer in heteroepitaxial systems is accommodated (at least partially) by the formation of misfit dislocations at the substrate/ epilayer interface. 6-10 These interfacial misfit dislocations are far from the metallurgical-junction interface and are believed to have minimal impact on diode performance. However, for a typical LWIR heterojunction-device structure, where a cap layer is grown on top of the absorber layer, misfit dislocations can theoretically form near the p-n junction at the cap/absorber interface.The formation of misfit dislocations at the interface between the substrate and the absorber layer and between the absorber layer and the cap depends on the misfit strain between the adjacent layers and the thickness of each layer. Because the location, density, and mobility of these misfit dislocations can degrade individual diode performance and, thus, Lattice mismatch between the substrate and the absorber layer in single-color HgCdTe infrared (IR) detectors and between band 1 and band 2 in two-color detectors results in the formation of crosshatch lines on the surface and an array of misfit dislocations at the epi-interfaces. Threading dislocations originating in the substrate can also bend into the interface plane and result in misfit dislocations because of the lattice mismatch. The existence of dislocations threading through the junction region of HgCdTe IR-photovoltaic detectors can greatly affect device performance. High-quality CdZnTe substrates and controlled molecular-beam epitaxy (MBE) growth of HgCdTe can result in very low threading-dislocation densities as measured by the etch-pit density (EPD ∼ 10 4 cm -2 ). However, dislocation gettering to regions of high stress (such as etched holes, voids, and implanted-junction regions) at elevated-processing temperatures can result in a high density of dislocations in the junction region that can greatly reduce detector performance. We have performed experiments to determine if the dislocations that getter to these regions of high stress are misfit dislocations at the substrate/absorber interface that have a threading component extending to the upper surface of t...

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“…Using SAD in this way has been called "epitaxial necking" 18 or "aspect ratio trapping" (ART) 19 . While ART is very efficient in removing 60°-dislocations, it does not eliminate so-called "growth dislocations" which are oriented along the growth direction 22,23 , unless it is combined with surface faceting. The expulsion of TDs by surface faceting is a result of their tendency to bend into directions perpendicular to a facet 23,24,25 .…”

Section: Introductionmentioning

confidence: 99%

X-Ray Nano-Diffraction on Epitaxial Crystals

Meduňa¹,

Falub²,

Isa³

et al. 2014

Quant. Matt

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The concept of growing epitaxial Ge and SiGe crystals onto tall Si pillars may provide a means for solving the problems associated with lattice parameter and thermal expansion coefficient mismatch, i.e., dislocations, wafer bowing and cracks. For carefully tuned epitaxial growth conditions the lateral expansion of crystals stops once nearest neighbors get sufficiently close. We have carried out scanning nano-diffraction experiments at the ID01 beam-line of the European Synchrotron Radiation Facility (ESRF) in Grenoble on the resulting space-filling arrays of micron-sized crystals to assess their structural properties and crystal quality. Elastic relaxation of the thermal strain causes lattice bending close to the Si interface, while the dislocation network is responsible for minute tilts of the crystals as a whole. To exclude any interference from nearest neighbors, individual Ge crystals were isolated first by chemical etching followed by micro-manipulation inside a scanning electron microscope. This permitted us to scan an X-ray beam, focused to a spot a few hundreds of nm in size, along the height of a single crystal and to record three-dimensional reciprocal space maps at chosen heights. The resolution limited width of the scattered X-ray beams reveals that the epitaxial structures evolve into perfect single crystals sufficiently far away from the heavily dislocated interface.

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Nature, origin and effect of dislocations in epitaxial semiconductor layers

Cited by 68 publications

References 2 publications

A Structural Characterization of GaAs MBE Grown on Si Pillars

A Structural Characterization of GaAs MBE Grown on Si Pillars

Threading and misfit-dislocation motion in molecular-beam epitaxy-grown HgCdTe epilayers

X-Ray Nano-Diffraction on Epitaxial Crystals

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