摘要: A novel crystal growth method has been developed for the production of ingots, bricks
and wafers for solar cells. Monocrystallinity is achievable over large volumes with minimal
dislocation incorporation. The resulting defect types, densities and interactions are described both
microscopically for wafers and macroscopically for the ingot, looking closely at the impact of the
defects on minority carrier lifetime. Solar cells of 156 cm2 size have been produced ranging up to
17% in efficiency using industrial screen print processes.
摘要: The carrier recombination activities of small angle (SA) grain boundaries (GBs) in
multicrystalline Si (mc-Si) were systematically investigated by electron-beam-induced current
(EBIC). At 300 K, general SA-GBs with tilt angle from 0° to 10° showed weak EBIC contrast (0-
10%) with the maximum appeared at 2°. At low temperature (100 K), all the SA-GBs showed
strong EBIC contrast despite the tilt angle. Possible explanations for the variation of the EBIC
contrast were discussed in terms of boundary dislocations.
摘要: This paper investigates the impact of iron (Fe) and molybdenum (Mo) when they are
introduced in the feedstock for mono- and multicrystalline Float-Zone (FZ) silicon (Si) growth.
Neutron Activation Analysis shows that the segregation coefficient is in agreement with literature
values. Lifetime maps on monocrystalline wafers show a uniform lifetime which decreases with the
increase of contamination levels. Multicrystalline wafers show low lifetime areas, corresponding to
grain boundaries and highly dislocated areas, which are independent from the contamination levels.
Intra grain areas have a higher lifetime which changes with the contamination levels. The solar cells
show a reduced diffusion length in multicrystalline uncontaminated cells compare to the
monocrystalline uncontaminated. In multicrystalline cells the lowest level of Fe introduced (1012
atm/cm3) has hardly any influence, whereas in the Mo-contaminated cells the impact is visible from
the lowest level (1011 atm/cm3). In monocrystalline cells the diffusion length is reduced already at
the lowest contamination level of Fe.
摘要: In present work temperature stable conductivity is considered for neutron-doped
FZ silicon with point radiation defects. It was shown that divacancy formed after electron
irradiation allow to increase resistivity of silicon at room temperature, what lead to less
variation of conductivity in a range of temperatures 20-160C. Discrepancy between
experimental and theoretical data was evaluated and corrected with introduction in the
model deep level center Ec-0.6eV. As result of investigation power resistors were
elaborated with 10% deviation from nominal value within the range of temperatures.
摘要: The knowledge and control of the structural and morphological properties of
nanocrystalline silicon is a fundamental requisite for its proper application in photovoltaics. To this
purpose, nanocrystalline silicon films grown by Low Energy Plasma Enhanced Chemical Vapour
Deposition (LEPECVD) technique on different kinds of substrates were submitted to a systematic
characterization using Raman spectroscopy, X-ray diffraction (XRD) and high-resolution
transmission electron microscopy (HRTEM). The results showed that the nature of the film
substrate induces deep changes in the structural properties of the deposited films. The importance of
a Raman in–depth analysis for an accurate determination of the sample structure has been also
摘要: Epitaxial group-III nitride films, although in single crystalline form, contain still a large
number of threading dislocations. These set limits to performance and lifetime of devices, notably
to high power structures like lasers. The strategy in material development was and will be (at least
until lattice-matched substrates become available) to reduce the dislocation densities. The present
contribution elaborates on possible dislocation origination mechanisms that determine the
population of dislocations in the epitaxial layers. These mechanisms can be controlled to a certain
degree by proper deposition procedures. The achieved dislocation populations then determine the
processes that can reduce the dislocation densities during growth of the epitaxial layers. The mutual
annihilation of threading dislocations is rather efficient although affected by the glide properties of
the growing epitaxial crystal and the thermal stresses during the cooling down after growth.
摘要: In this paper, the deep levels occurring in Fe- or Co-germanide Schottky barriers on ntype
Ge have been studied by Deep Level Transient Spectroscopy (DLTS). As is shown, no traps
have been found for germanidation temperatures up to 500 oC, suggesting that in both cases no
marked metal in-diffusion takes place during the Rapid Thermal Annealing (RTA) step. Deep
acceptor states in the upper half of the Ge band gap and belonging to substitutional Co and Fe can
be detected by DLTS only at higher RTA temperatures (TRTA). For the highest TRTA, deep levels
belonging to other metal contaminants (Cu) have been observed as well. Simultaneously, the reverse
current of the Schottky barriers increases with TRTA, while the barrier height is also strongly