Abstract
Growth and characterization of advanced group IV semiconductor materials with CMOS‐compatible applications are demonstrated, both in photonics. The investigated GeSn/SiGeSn heterostructures combine direct bandgap GeSn active layers with indirect gap ternary SiGeSn claddings, a design proven its worth already decades ago in the III–V material system. Different types of double heterostructures and multi‐quantum wells (MQWs) are epitaxially grown with varying well thicknesses and barriers. The retaining high material quality of those complex structures is probed by advanced characterization methods, such as atom probe tomography and dark‐field electron holography to extract composition parameters and strain, used further for band structure calculations. Special emphasis is put on the impact of carrier confinement and quantization effects, evaluated by photoluminescence and validated by theoretical calculations. As shown, particularly MQW heterostructures promise the highest potential for efficient next generation complementary metal‐oxide‐semiconductor (CMOS)‐compatible group IV lasers.
Highlights
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We report on growth and characterization of various types of GeSn/SiGeSn heterostructures, combining for the first time relaxed direct bandgap GeSn active layers with SiGeSn barriers
In comparison to laser structures reported earlier in literature,[12,14] introduction of different SiGeSn claddings for carrier confinement does not result in improved lasing thresholds
Summary
IV photonics is the key technology,[2,3] allowing seamless integration of comwith CMOS-compatible applications are demonstrated, both in photonics. In comparison to laser structures reported earlier in literature,[12,14] introduction of different SiGeSn claddings for carrier confinement does not result in improved lasing thresholds Their theoretical advantage seems to be shadowed by a common drawback of both structures: a newly formed misfit dislocation network at the GeSn/SiGeSn interface, making the structures behave similar to bulk GeSn layers. We expect a distinct advantage of MQW heterostructures, compared to double heterostructures and even more bulk GeSn layers These features may allow room temperature, low threshold lasers made entirely from group IV materials. For the MQW heterostructures, a shift in light emission is achieved by controlling the quantum confinement of carriers through varying well thicknesses Most importantly, this type of structure outperforms double heterostructures, because of the spatial separation of misfit dislocations from the active region. We believe that, as demonstrated decades ago already for the III–V material system, group IV heterostructures and multi-quantum wells are potential enablers for high efficient integrated light emitters
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