Carrier Recombination Dynamics of Surface Passivated Epitaxial (100)Ge, (110)Ge, and (111)Ge Layers by Atomic Layer Deposited Al2O3

dc.contributor.authorHudait, Mantu K.en
dc.contributor.authorJohnston, Steven W.en
dc.contributor.authorDas, Manash R.en
dc.contributor.authorKarthikeyan, Senguntharen
dc.contributor.authorSahu, Partha P.en
dc.contributor.authorDas, Jagaten
dc.contributor.authorZhao, Jingen
dc.contributor.authorBodnar, Robert J.en
dc.contributor.authorJoshi, Rutwiken
dc.date.accessioned2025-03-04T13:38:33Zen
dc.date.available2025-03-04T13:38:33Zen
dc.date.issued2023-05-24en
dc.description.abstractGermanium (Ge) and its heterostructures with compound semiconductors offer a unique optoelectronic functionality due to its pseudo-bandgap nature, that can be transformed to a direct bandgap material by providing strain and/or mixing with tin. Moreover, two crystal surfaces, (100)Ge and (110)Ge, that are technologically important for ultralow power fin or nanosheet transistors, could offer unprecedented properties with reduced surface defects after passivating these surfaces by atomic layer deposited (ALD) dielectrics. In this work, the crystallographically oriented epitaxial Ge/AlAs heterostructures were grown and passivated with ALD Al2O3 dielectrics, and the microwave photoconductive decay (μ-PCD) technique was employed to evaluate carrier lifetimes at room temperature. The X-ray photoelectron spectroscopy analysis reveals no role of orientation effect in the quality of the ALD Al2O3 dielectric on oriented Ge layers. The carrier lifetimes measured using the μ-PCD technique were benchmarked against unpassivated Ge/AlAs heterostructures. Excitation wavelengths of 1500 and 1800 nm with an estimated injection level of ∼1013 cm-3 were selected to measure the orientation-specific carrier lifetimes. The carrier lifetime was increased from 390 ns to 565 ns for (100)Ge and from 260 ns to 440 ns for (110)Ge orientations with passivation, whereas the carrier lifetime is almost unchanged for (111)Ge after passivation. This behavior indicates a strong dependence of the measured lifetime on surface orientation and surface passivation. The observed increase (>1.5×) in lifetime with Al2O3-passivated (100)Ge and (110)Ge surfaces is due to the lower surface recombination velocity compared to unpassivated Ge/AlAs heterostructures. The enhancement of carrier lifetime from passivated Ge/AlAs heterostructures with (100)Ge and (110)Ge surface orientations offers a path for the development of nanoscale transistors due to the reduced interface state density.en
dc.description.versionAccepted versionen
dc.format.extentPages 3190-3197en
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1021/acsaelm.3c00383en
dc.identifier.eissn2637-6113en
dc.identifier.issn2637-6113en
dc.identifier.issue6en
dc.identifier.orcidHudait, Mantu [0000-0002-9789-3081]en
dc.identifier.orcidBodnar, Robert [0000-0002-3549-2071]en
dc.identifier.urihttps://hdl.handle.net/10919/124767en
dc.identifier.volume5en
dc.language.isoenen
dc.publisherACSen
dc.relation.urihttps://pubs.acs.org/doi/10.1021/acsaelm.3c00256en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectgermaniumen
dc.subjectAl2O3en
dc.subjectmolecularbeam epitaxyen
dc.subjectX-ray photoelectron spectroscopyen
dc.subjectlifetimeen
dc.subjectatomic layer depositionen
dc.titleCarrier Recombination Dynamics of Surface Passivated Epitaxial (100)Ge, (110)Ge, and (111)Ge Layers by Atomic Layer Deposited Al<sub>2</sub>O<sub>3</sub>en
dc.title.serialACS Applied Electronic Materialsen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.otherArticleen
pubs.organisational-groupVirginia Techen
pubs.organisational-groupVirginia Tech/Scienceen
pubs.organisational-groupVirginia Tech/Science/Geosciencesen
pubs.organisational-groupVirginia Tech/Engineeringen
pubs.organisational-groupVirginia Tech/Engineering/Electrical and Computer Engineeringen
pubs.organisational-groupVirginia Tech/University Distinguished Professorsen
pubs.organisational-groupVirginia Tech/All T&R Facultyen
pubs.organisational-groupVirginia Tech/Engineering/COE T&R Facultyen
pubs.organisational-groupVirginia Tech/Science/COS T&R Facultyen

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