We first reported on a process for on-axis InSb crystal growth in 2014. As we have further developed on-axis (111) crystal growth, we have observed and measured a new distinct regime of interface-controlled dopant segregation. This effect is usually overshadowed by the facet effect and the resulting order of magnitude step change in the carrier concentration profile. When this large step change is eliminated, another interface-controlled effect becomes measurable. We present experimental data showing the magnitude of this effect and the crystal growth techniques used to engineer the interface where this effect is uncovered. We also discuss the atomic scale growth mechanisms that explain it.
This work proves useful in predicting the range of mechanical and electronic properties of wafers cut from ingots that are grown on-axis. More specifically, by understanding the effect of the melt/solid growth interface on the physical properties on the crystal, growth conditions can be optimized to produce more electrically uniform wafers that minimize pixel-to-pixel variation in FPAs.
InSb focal plane array (FPA) detectors are key components in IR imaging systems that significantly impact both cost and
performance. Detector performance is affected by the electronic and crystallographic quality and uniformity of the
semiconductor substrate. High-volume, high-yield production of InSb wafers to the standards required for FPA device
manufacture requires growth of on-axis {111} crystals. An inherent source of variation hindering on-axis Czochralski
crystal growth is anisotropic dopant incorporation. We report on newly developed growth methods that eliminate the
negative effects of anisotropic dopant incorporation enabling high volume manufacturing of {111}-oriented substrates
and discuss the consequential manufacturing benefits. We also report on a characterization technique to characterize
microscale dopant variation across the wafer.
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