In-situ monitoring of InP(100) and GaP(100) interfaces and characterization with RDS at 20 K

Hannappel, T.; Töben, L.; Möller, K.; Willig, F.

doi:10.1007/s11664-001-0196-7

Cited by 33 publications

(34 citation statements)

References 18 publications

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“…Below 775 K, the TBP stabilization was turned off which led to P depletion and an In-rich (2 × 4) reconstructed surface. [22][23][24] P-atoms form a mixed dimer with In-atoms along the [-110] direction that terminate the surface while In-bonds extend in [110] direction and complete the (2 × 4) reconstruction (see Figure 1a).(Photo)electrochemistry was carried out in a three-electrode arrangement with a Pt counter electrode for surface conditioning; a carbon electrode was used for efficiency tests. A saturated calomel (SCE) electrode was used as reference and all potentials are referred to SCE.…”

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confidence: 99%

Photoelectrochemical Conditioning of MOVPE p-InP Films for Light-Induced Hydrogen Evolution: Chemical, Electronic and Optical Properties

Muñoz¹,

Heine²,

Lublow³

et al. 2013

ECS J. Solid State Sci. Technol.

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Homoepitaxial p-InP(100) thin films prepared by MOVPE (metallorganic vapor phase epitaxy) were transformed into an InP/oxidephosphate/Rh heterostructure by photoelectrochemical conditioning. Surface sensitive synchrotron radiation photoelectron spectroscopy indicates the formation of a mixed oxide constituted by In(PO 3 ) 3 , InPO 4 and In 2 O 3 as nominal components during photo-electrochemical activation. The operation of these films as hydrogen evolving photocathode proved a light-to-chemical energy conversion efficiency of 14.5%. Surface activation arises from a shift of the semiconductor electron affinity by 0.44 eV by formation of In-Cl interfacial dipoles with a density of about 10 12 cm −2 . Predominant local In 2 O 3 -like structures in the oxide introduce resonance states near the semiconductor conduction band edge imparting electron conductivity to the phosphate matrix. Surface reflectance investigations indicate an enhanced light-coupling in the layered architecture. Solar hydrogen generation from water represents a viable route for establishing a carbon-neutral energy infrastructure based on renewable energy resources.1-4 To achieve this long-term objective, numerous approaches are currently being pursued comprising adapting systems derived from photosynthesis, 5-7 identification of appropriate catalysts, 8 development of transition metal oxide photoelectrodes 9,10,11 as well as devising efficient semiconductor tandem structures.12-14 Because biomimetic systems inspired by natural photosynthesis are characterized by rather low theoretical efficiencies, 6 the use of photoresponsive semiconductor materials for the splitting of water appears currently most promising. It can be shown that dual-bandgap systems reach theoretically efficiencies well above 40% at AM1.5. 15 The development horizon suggests therefore the use of technologically advanced semiconductor materials which would allow comparably fast technical realization. Further, the orthogonalization of charge carrier and photon pathways as well as an increased built-in potential by interfacial doping was recently exploited to achieve efficiencies near 10% using Si as substrate. 16 p-type InP is one of the most efficient photocathode materials for hydrogen evolution available. Heller and Vadimsky 17 have shown three decades ago that hydrogen evolution can occur with an efficiency of 12% if rhodium is deposited as catalytically active and optically transparent thin-film on top of an In 2 O 3 /InP structure. In this work, a new approach based on thin film photoelectrodes is presented. The photocathode is realized by homoepitaxial growth of thin films onto InP wafers which allows the use of liftoff procedures already known for photovoltaic systems. 18,19 The removal of the thin film photocathodes from the growth substrate is thereby possible after fabrication of the devices. This approach reduces production costs, which is a decisive factor for many III-V devices. In this report, we evaluate the applicability of homoepitaxial devices with emphasis in...

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confidence: 99%

Photoelectrochemical Conditioning of MOVPE p-InP Films for Light-Induced Hydrogen Evolution: Chemical, Electronic and Optical Properties

Muñoz¹,

Heine²,

Lublow³

et al. 2013

ECS J. Solid State Sci. Technol.

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“…More recently also very thin (several monolayers) films of highly anisotropic organic molecules as e.g. PTCDA [2] and parasexiphenyl [3] were characterised using RAS and also in situ growth monitoring was performed by RAS [3,4].…”

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In‐plane optical anisotropy of copper‐phthalocyanine films: RAS studies and modelling

Fronk

Zahn

Salvan

2010

Phys. Status Solidi (c)

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Copper‐phthalocyanine (CuPc) films prepared by organic molecular beam deposition on H‐passivated silicon and Si covered with native oxide were investigated by means of ellipsometry and reflection anisotropy spectroscopy (RAS). In addition to the out‐of‐plane anisotropy found from the evaluation of the ellipsometry data (Aspnes and Studna, Phys. Rev. Lett. 54, 1954 (1985) [1]) an in‐plane anisotropy in the order of 10‐2 was detected by RAS. In a first step model calculations assuming homogeneous in‐plane anisotropy over the whole layer thickness were performed in order to extract the anisotropy of the optical constants n and k. In a second step, more advanced models taking into account a change in the anisotropy with film thickness were constructed in order to describe the in‐plane anisotropy spectral evolution with film thickness. For the films on Si/SiO2 the in‐plane anisotropy is found to increase with increasing thickness. On H‐Si this effect is not observed and the behaviour of CuPc is more complicated to model on this substrate. Thus, the interaction of the molecules with the differently treated substrate surfaces plays a crucial role for the molecular alignment. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…A pronounced negative peak below the energetic position of the interband transition E 0 [9,15]. This peak is only induced by electronic transitions of the surface Brillouin zone and appears just at slightly different energetic positions for the Ga-rich and the P-rich surface reconstruction.…”

Section: Introductionmentioning

confidence: 98%

“…The InP(1 0 0) surface reconstructs in the same surface reconstructions as evidenced by several theoretical [11] and experimental [12,13] studies. The (2 Â 2)/c(4 Â 2) P-rich surfaces can only be obtained in the presence of hydrogen (available as a carrier gas in the MOVPE environment and as fragments of the precursor pyrolysis) [9,12,14,15]. In the low energy electron diffraction (LEED) image these surfaces result in a (2 Â 1) pattern with streaks at half order in the Â 1 direction [12].…”

Section: Introductionmentioning

confidence: 99%

“…To monitor surfaces of III-V compound semiconductors in a MOVPE environment and their relative changes according to different MOVPE preparation parameters like temperature, group V partial pressure, or variations of the carrier gas, in situ reflectance anisotropy spectroscopy (RAS) has been utilized in various studies [15][16][17]. Here, the resulting RA spectra can be regarded as characteristic 'fingerprints' of the different surface reconstructions.…”

Section: Introductionmentioning

confidence: 99%

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GaP(1 0 0) and InP(1 0 0) surface structures during preparation in a nitrogen ambient

Döscher

Möller

Hannappel

2011

Journal of Crystal Growth

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In-situ monitoring of InP(100) and GaP(100) interfaces and characterization with RDS at 20 K

Cited by 33 publications

References 18 publications

Photoelectrochemical Conditioning of MOVPE p-InP Films for Light-Induced Hydrogen Evolution: Chemical, Electronic and Optical Properties

Photoelectrochemical Conditioning of MOVPE p-InP Films for Light-Induced Hydrogen Evolution: Chemical, Electronic and Optical Properties

In‐plane optical anisotropy of copper‐phthalocyanine films: RAS studies and modelling

GaP(1 0 0) and InP(1 0 0) surface structures during preparation in a nitrogen ambient

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