TY - GEN A1 - Dorp, Dennis H. von A1 - Nyns, Laura A1 - Cuypers, Daniel A1 - Ivanov, Tsvetan A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Fleischmann, Claudia A1 - Hönicke, Philipp A1 - Müller, Matthias A1 - Richard, Olivier A1 - Schmeißer, Dieter A1 - De Gendt, Stefan A1 - Lin, Dennis H. C. A1 - Adelmann, Christoph T1 - Amorphous Gadolinium Aluminate as a Dielectric and Sulfur for Indium Phosphide Passivation T2 - ACS Applied Electronic Materials N2 - The passivation of n-type InP (100) using sulfur in combination with a gadolinium aluminate (GAO) dielectric layer has been studied. Photoluminescence, minority-carrier lifetime, and capacitance−voltage measurements indicate that a (NH4)2S vapor passivation step prior to atomic layer deposition of the oxide effectively lowers the interface state density. Surface and interface chemistry were studied by synchrotron radiation photoemission spectroscopy (SRPES). The effect of ex situ surface passivation after native oxide removal in HCl solution was examined. It was observed that surface reoxidation occurred during (NH4)2S vapor exposure, leading to the formation of Inx(HPO4)y. S was present on the surface as a sulfide in both surface and subsurface sites. After atomic layer deposition of GAO, sulfates were detected in addition to Inx(HPO4)y, which was confirmed by near-edge X-ray absorptionfine structure analysis. The S in the stack was quantified using reference-free grazing incidence X-rayfluorescence analysis. X-ray absorption spectroscopy showed that Gd was oxidized and present in the 3+ oxidation state, most likely as a phosphate close to the InP interface and possibly mixed with sulfates. Energy-dependent SRPES measurements of Al 2p and Gd 4d core levels, complemented by transmission electron microscopy, further suggest that the dielectric layer was segregated. Valence band measurements confirm the effective passivation of InP, indicating unpinning of the surface Fermi level. KW - III−V KW - InP KW - sulfur passivation KW - atomic layer deposition KW - gadolinium aluminate KW - rare earth oxide KW - dielectric Y1 - 2019 U6 - https://doi.org/10.1021/acsaelm.9b00388 SN - 2637-6113 VL - 1 IS - 11 SP - 2190 EP - 2201 ER - TY - GEN A1 - Cuypers, Daniel A1 - Fleischmann, Claudia A1 - Dorp, Dennis H. von A1 - Brizzi, Simone A1 - Tallarida, Massimo A1 - Müller, Matthias A1 - Hönicke, Philipp A1 - Billen, Arne A1 - Chintala, Ravi A1 - Conard, Thierry A1 - Schmeißer, Dieter A1 - Vandervorst, Wilfried A1 - Elshocht, Sven van A1 - Armini, Silvia A1 - De Gendt, Stefan A1 - Adelmann, Christoph T1 - Sacrificial Self-Assembled Monolayers for the Passivation of GaAs(100) Surfaces and Interfaces T2 - Chemistry of Materials N2 - The use of sacrificial self-assembled monolayers (SAMs) to prepare clean n-type GaAs (100) surfaces without band bending in vacuo is demonstrated. GaAs surface passivation using octadecanethiol SAMs after HCl cleaning is shown to lead to an enhancement of the room-temperature photoluminescence intensity. Synchrotron-radiation photoelectron spectroscopy (SRPES) finds that the interfacial oxide between GaAs and the SAM remains below the detection limit. Evidence for both Ga–S and As–S bonds at the GaAs–thiolate interface is found. The limited thermal stability of the SAM allows the desorption of the alkyl chains by in situ thermal annealing at temperatures above 180 °C, leaving S bonded to Ga behind. The resulting surface contains only a very small amount of O (0.05 ML coverage) and C (about 3% of the SAM remaining) and shows no band bending with the surface Fermi level close to the conduction band. Atomic layer deposition of Al₂O₃ on this surface occurs via the formation of Al–S bonds without introducing any additional band bending. This indicates that the surface preparation of n-type GaAs (100) using sacrificial octadecanethiol SAMs followed by in situ thermal removal provides a route toward GaAs/oxide interfaces without interfacial oxides and without band bending. KW - GaAs KW - passivation KW - Al₂O₃ KW - atomic layer deposition (ALD) KW - Synchrotron-radiation photoelectron spectroscopy (SRPES) KW - self assembled monolayers (SAM) KW - interface engineering Y1 - 2016 U6 - https://doi.org/10.1021/acs.chemmater.6b01732 SN - 0897-4756 SN - 1520-5002 VL - 28 IS - 16 SP - 5689 EP - 5701 ER -