Junction formation of Cu₃BiS₃ investigated by Kelvin probe force microscopy and surface photovoltage measurements

• Fredy Mesa,
• William Chamorro,
• William Vallejo,
• Robert Baier,
• Thomas Dittrich,
• Alexander Grimm,
• Martha C. Lux-Steiner and
• Sascha Sadewasser

Beilstein J. Nanotechnol. 2012, 3, 277–284, doi:10.3762/bjnano.3.31

• distribution for In2S3 compared to that of CdS and ZnS. For In2S3 and CdS buffer layers the KPFM experiments indicate negatively charged Cu3BiS3 grain boundaries resulting from the deposition of the buffer layer. Macroscopic measurements of the surface photovoltage at variable excitation wavelength indicate

• , such as chemical bath deposition, atomic layer deposition, ion layer gas reaction (ILGAR) deposition, evaporation, and spray deposition [9]. One interesting aspect of the above mentioned solar cell materials CdTe and Cu(In,Ga)Se2 is their high efficiency despite the abundance of grain boundaries (GBs

• ). Scanning probe microscopy experiments have provided significant insight into the physics of grain boundaries on these materials [10]. Specifically, recent experiments provided evidence for the benign properties of the GBs [11][12], in agreement with previous theoretical work [13][14]. Also the influence of

Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films

• Luyang Han,
• Ulf Wiedwald,
• Johannes Biskupek,
• Kai Fauth,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 473–485, doi:10.3762/bjnano.2.51

• exhibiting grain sizes (20–30 nm) smaller than the particle spacing (100 nm), the formation of local nanoalloys at the surface is strongly suppressed and Co incorporation into the film via grain boundaries is favoured. In contrast, due to the absence of grain boundaries on high quality epitaxial Pt(100

• restricted by a photoelectron mean free path of about 1.6 nm [27]. Rather, diffusion along the large number of grain boundaries in the Pt(111) film on MgO(100) is expected. On Pt(100) films with micron-sized, atomically-flat surfaces this diffusion channel does not exist for most of the NPs, thus markedly

• reduced Co content after annealing suggests that Co atoms diffuse away from the surface along grain boundaries at elevated temperature. Thus, we speculate that after annealing the size-reduced NPs on Pt(111) remain in a pure Co, or at least Co-rich, phase having a rather low orbital moment. Nevertheless

Formation of precise 2D Au particle arrays via thermally induced dewetting on pre-patterned substrates

• Dong Wang,
• Ran Ji and
• Peter Schaaf

Beilstein J. Nanotechnol. 2011, 2, 318–326, doi:10.3762/bjnano.2.37

• agglomeration [32][33], voids can nucleate due to periodic film thickness fluctuations (spinodal dewetting), or at defects, which is then followed by void growth and particle formation [31]. For polycrystalline metallic films, dewetting is also affected by the character of grain boundaries [33]. Altogether

• , and then proceeds with void growth and particle formation. For polycrystalline films on the flat substrates, void nucleation is generally thought to occur due to grain boundary grooving, via surface diffusion at the grain boundaries, and grain boundary triple junctions which intersect the substrate

• surface [39][40]. Recently, Mueller and Spolenak have reported that holes (large substrate-exposing voids) were found to protrude into the film predominantly at high angle grain boundaries during dewetting [41]. During annealing, grain boundary grooving and grain growth are competing kinetic processes

Schottky junction/ohmic contact behavior of a nanoporous TiO₂ thin film photoanode in contact with redox electrolyte solutions

• Masao Kaneko,
• Hirohito Ueno and
• Junichi Nemoto

Beilstein J. Nanotechnol. 2011, 2, 127–134, doi:10.3762/bjnano.2.15

• are transported first to the fluorine-doped tin oxide (FTO, SnO2:F) conductive layer through TiO2 grain boundaries and then to the cathode reducing electron acceptor there (O2 in the present case). In a Schottky junction, under the conditions when the band structure is flat without any bending, the

• . The thin space charge layer is located at the interface between TiO2 and the liquid, and the band structure (CB and VB) in the TiO2 bulk is interconnected through the TiO2 grain boundaries forming continuous CB electron-transporting channels from the space charge layer to reach the conductive layer on

• separated into electrons and holes due to the slope of the VB and CB bands, the h+ then being reduced by MeOH present in the liquid, and the e− being transported in the CB through TiO2 grain boundaries to the counter cathode via the FTO. As reported earlier by us [13], resistances at the grain boundaries

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

• Thomas König,
• Georg H. Simon,
• Lars Heinke,
• Leonid Lichtenstein and
• Markus Heyde

Beilstein J. Nanotechnol. 2011, 2, 1–14, doi:10.3762/bjnano.2.1

• trapped charge on the surface dipole. This demonstrates the great benefit of NC-AFM and KPFM in combination with STM and STS. Line defects Apart from point defects more complex structures like line defects are found on oxide surfaces. Line defects can be caused by step edges or grain boundaries that