Negative magnetoresistance in silicon doped with manganese

3 Results and their discussion 
As demonstrated by the results of investigations in samples of I-party at T=300 K obtained 
by new technology p-
Si with Fermi level position in EF=EV+(0.38÷0.45) eV, the 
superfine ESR spectra consisting of 21 lines (Fig. 2.a) characteristic for nanoclusters 
containing four manganese atoms [22] are clearly observed. With shift of Fermi level from 
EF=EV+(0.38÷0.45) to the middle of forbidden zone F=EV+(0.52÷0.55) eV the ESR 
spectra are observed which intensity decreases due to decrease of atoms concentration in 
[Mn]++ state and corresponding increase of atoms concentration in Mn+ state. 
Fig. 2a.
ESR spectrum of [Mn]4 in silicon
Fig. 2b.
ESR spectrum of manganese Mn++ 
atoms in silicon 
In samples of II party alloyed on usual technology were obtained samples Si of p-
type conductivity with similar parameters (resistivity), the same as in samples obtained on 
new technology, where nanoclusters of manganese atoms were observed, However in these 
samples Si irrespective of their parameters ESR has not shown presence of 
nanoclusters of manganese atoms and also in overcompensated Si n-type samples 
obtained by new technology not depending on position of Fermi level in them. The ESR 
spectra observed in these cases are associated with a single state of manganese atoms (Fig. 
2.b). 
As a result of a creative collaboration with the Seoul University Semiconductor 
Research Centre team from South Korea, we have been greatly assisted by the structural 
analysis of Mn-doped Si samples by our colleagues using an X-ray diffractometer (XRD, 
Rigaku mini flex). 
Figure 3 shows Si (111) diffraction peaks showing manganese boride (Mn4B) 
complexes. These results are direct evidence for the formation of magnetic clusters of 
impurity atoms in the silicon lattice. 
E3S Web of Conferences 
401
, 05094 (2023)
CONMECHYDRO - 2023
https://doi.org/10.1051/e3sconf/202340105094
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Fig. 3.
X-ray spectra of magnetic clusters. 
It should be noted that in n-type silicon samples doped with manganese as well as in 
overcompensated samples no spectra associated with nanoclusters of manganese atoms are 
observed. Therefore, we can say with certainty that low-temperature doping is a new 
technological solution for the formation of nanoclusters of impurity atoms in the silicon 
lattice. This is a fundamentally new approach to the formation of nanoscale structures in the 
semiconductor lattice, which does not require expensive technological equipment. As 
shown by ESR studies, in samples where nanoclusters of manganese atoms are observed 
spectra, nanoclusters are observed throughout the entire sample volume. We stepwise 
grinded 30÷50 μm from the sample surface to half
of the sample thickness and after each 
grinding step the ESR spectra were taken, which were the same each time without 
significant changes. These results clearly show that nanoclusters and nanoscale structures 
can form throughout the entire crystal volume. 
Therefore, we assume that the structure of a magnetic nanocluster consists of four 
positively charged manganese atoms, which are in the nearest equivalent inter-nodes 
around a negatively charged boron atom. The nanoclusters of manganese atoms can act as 
magnetic centres because the clusters consist of four manganese atoms with spins S=5/2 
and total spin 4S=10, i.e. they should act as a powerful magnetic moment and lead to a 
significant change in the anomalous Hall effect. 
Results of researches of electro-physical properties of the received material have shown, 
that in samples from I party the new galvanomagnetic phenomenon which essence consists 
that the Hall voltage drop in these samples considerably differs in comparison with samples 
of II party is observed. With a change of 2-3 times the polarity of the magnetic field, the 
Hall voltage drop of the electric field is observed. This difference is more clearly seen in 
those samples where there are magnetic nanoclusters of manganese atoms. In the 
compensated samples from batch II, as well as in the overcompensated samples, regardless 
of their resistivity, the usual Hall mobility of charge carriers is observed, practically 
comparable to the mobility of charge carriers without impurity atoms. 
Results of research of anomalous Hall effect in samples of I party depending on 
resistivity of samples showed that effect has the maximum value in samples of p-type with 
ρ=7·103 Ом·cм, in range 5·10
3
Ohm·cm>ρ>10
4
Ohm·cm it weakens, and in samples with 
resistivity 3·10
2
Ohm·cm>ρ>1,2·10
5
Ohm·cm and in n
-type samples with a wide range of 
resistivity the usual Hall effect is observed, i.e. the anomalous Hall effect is canceled
(Table 1). 
E3S Web of Conferences 
401
, 05094 (2023)
CONMECHYDRO - 2023
https://doi.org/10.1051/e3sconf/202340105094
5

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