Surface passivation of Germanium with ALD Al2O3: Impact of Composition and Crystallinity of GeOx Interlayer

dc.contributorAalto Universityen
dc.contributor.authorIsometsä, Joonas
dc.contributor.authorRad, Zahra Jahanshah
dc.contributor.authorFung, John
dc.contributor.authorLiu, Hanchen
dc.contributor.authorLehtiö, Juha Pekka
dc.contributor.authorPasanen, Toni
dc.contributor.authorLeiviskä, Oskari
dc.contributor.authorMiettinen, Mikko
dc.contributor.authorLaukkanen, P.
dc.contributor.authorKokko, K.
dc.contributor.authorSavin, Hele
dc.contributor.authorVähänissi, Ville
dc.contributor.departmentHele Savin Group
dc.contributor.departmentUniversity of Turku
dc.contributor.departmentDepartment of Electronics and Nanoengineering
dc.description.abstractGermanium is an excellent material candidate for various applications, such as field-effect transistors and radiation detectors / multi-junction solar cells, due to its high carrier mobilities and narrow bandgap, respectively. However, efficient passivation of germanium surfaces has 10 remained challenging. Recently the most promising results have been achieved with atomic layer deposited (ALD) Al2O3, but the obtainable surface recombination velocity (SRV) has been very sensitive to the surface state prior to deposition. Based on X-ray photoelectron spectroscopy (XPS) and Low-energy electron diffraction (LEED), we show here that the poor SRV obtained with the combination of HF and DIW surface cleaning and ALD Al2O3 results from a Ge suboxide interlayer (GeOx, x < 2) with compromised quality. Nevertheless, our results also demonstrate that both the composition and crystallinity of this oxide layer can be improved by a combination of low-temperature heating and a 300-Langmuir controlled oxidation in ultrahigh-vacuum (LT-UHV treatment). This results in the reduction of the interface defect density (Dit) allowing us to reach SRV values as low as 10 cm/s. Being compatible with most device processes due to the low thermal budget, the LT-UHV treatment could be easily integrated into many future devices and applications.en
dc.description.versionPeer revieweden
dc.identifier.citationIsometsä , J , Rad , Z J , Fung , J , Liu , H , Lehtiö , J P , Pasanen , T , Leiviskä , O , Miettinen , M , Laukkanen , P , Kokko , K , Savin , H & Vähänissi , V 2023 , ' Surface passivation of Germanium with ALD Al2O3: Impact of Composition and Crystallinity of GeOx Interlayer ' , Crystals , vol. 13 , no. 4 , 667 .
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dc.publisherMDPI AG
dc.relation.ispartofseriesarticlenumber 667en
dc.subject.keywordSurface passivation
dc.subject.keywordAtomic layer deposition
dc.subject.keywordAluminum oxide
dc.subject.keywordUltra-high vacuum
dc.subject.keywordCorona oxide characterization of semiconductors
dc.subject.keywordQuasi-steady-state microwave detected photo-conductance decay
dc.subject.keywordX-Ray photoelectron spectroscopy
dc.subject.keywordLow-energy electron diffraction
dc.titleSurface passivation of Germanium with ALD Al2O3: Impact of Composition and Crystallinity of GeOx Interlayeren
dc.typeA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessäfi