Dataset Information

PO _x /Al₂O₃ Stacks for c-Si Surface Passivation: Material and Interface Properties.

ABSTRACT: Phosphorus oxide (PO _x ) capped by aluminum oxide (Al₂O₃) has recently been discovered to provide excellent surface passivation of crystalline silicon (c-Si). In this work, insights into the passivation mechanism of PO _x /Al₂O₃ stacks are gained through a systematic study of the influence of deposition temperature (T _dep = 100-300 °C) and annealing temperature (T _ann = 200-500 °C) on the material and interface properties. It is found that employing lower deposition temperatures enables an improved passivation quality after annealing. Bulk composition, density, and optical properties vary only slightly with deposition temperature, but bonding configurations are found to be sensitive to temperature and correlated with the interface defect density (D _it), which is reduced at lower deposition temperature. The fixed charge density (Q _f) is in the range of + (3-9) × 10¹² cm^-2 and is not significantly altered by annealing, which indicates that the positively charged entities are generated during deposition. In contrast, D _it decreases by 3 orders of magnitude (∼10¹³ to ∼10¹⁰ eV^-1 cm^-2) upon annealing. This excellent chemical passivation is found to be related to surface passivation provided by hydrogen, and mixing of aluminum into the PO _x layer, leading to the formation of AlPO₄ upon annealing.

SUBMITTER: Theeuwes RJ

PROVIDER: S-EPMC8552444 | biostudies-literature | 2021 Oct

REPOSITORIES: biostudies-literature

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Publications

PO x /Al2O3 Stacks for c-Si Surface Passivation: Material and Interface Properties.

Theeuwes Roel J RJ Melskens Jimmy J Black Lachlan E LE Beyer Wolfhard W Koushik Dibyashree D Berghuis Wilhelmus J H WJH Macco Bart B Kessels Wilhelmus M M WMM

ACS applied electronic materials 20211012 10

Phosphorus oxide (PO x ) capped by aluminum oxide (Al2O3) has recently been discovered to provide excellent surface passivation of crystalline silicon (c-Si). In this work, insights into the passivation mechanism of PO x /Al2O3 stacks are gained through a systematic study of the influence of deposition temperature (T dep = 100-300 °C) and annealing temperature (T ann = 200-500 °C) ...[more]

PMID: 34723186

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Project description:III/V semiconductor nanostructures have significant potential in device applications, but effective surface passivation is critical due to their large surface-to-volume ratio. For InP such passivation has proven particularly difficult, with substantial depassivation generally observed following dielectric deposition on InP surfaces. We present a novel approach based on passivation with a phosphorus-rich interfacial oxide deposited using a low-temperature process, which is critical to avoid P-desorption. For this purpose we have chosen a POx layer deposited in a plasma-assisted atomic layer deposition (ALD) system at room temperature. Since POx is known to be hygroscopic and therefore unstable in atmosphere, we encapsulate this layer with a thin ALD Al2O3 capping layer to form a POx/Al2O3 stack. This passivation scheme is capable of improving the photoluminescence (PL) efficiency of our state-of-the-art wurtzite (WZ) InP nanowires by a factor of ∼20 at low excitation. If we apply the rate equation analysis advocated by some authors, we derive a PL internal quantum efficiency (IQE) of 75% for our passivated wires at high excitation. Our results indicate that it is more reliable to calculate the IQE as the ratio of the integrated PL intensity at room temperature to that at 10 K. By this means we derive an IQE of 27% for the passivated wires at high excitation (>10 kW cm-2), which constitutes an unprecedented level of performance for undoped InP nanowires. This conclusion is supported by time-resolved PL decay lifetimes, which are also shown to be significantly higher than previously reported for similar wires. The passivation scheme displays excellent long-term stability (>7 months) and is additionally shown to substantially improve the thermal stability of InP surfaces (>300 °C), significantly expanding the temperature window for device processing. Such effective surface passivation is a key enabling technology for InP nanowire devices such as nanolasers and solar cells.

Dataset Information

PO _x /Al₂O₃ Stacks for c-Si Surface Passivation: Material and Interface Properties.

Publications

PO <sub><i>x</i></sub> /Al<sub>2</sub>O<sub>3</sub> Stacks for c-Si Surface Passivation: Material and Interface Properties.

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