Fotoenergetikada nanostrukturali yarimo‘tkazgich materiallar
II xalqaro ilmiy anjumani 19-20 noyabr 2021 yil 131
10
3
Ohm
cm. The measurements were carried out using an infrared spectrometer
IRS-21 at a temperature of 77
K . Dark photoconductivity in samples with
= 10
3
Ohm
cm started at h
= 0.3
eV and had a small peak at h
= 0.38
eV . In
i -type
samples with
= 10
5
Ohm
cm, the dark spectrum was monotonic. In these samples,
the dark photoconductivity increased monotonically starting with
h
0.5
eV .
The present paper reports the results of a study of the photoconductivity
spectrum of silicon samples doped with sulfur under dark conditions and under
constant illumination in forward and reverse connect modes and, accordingly, the
curves of dependence of the current in the samples on the energy of incident
photons are presented.
The authors investigated the photoconductivity spectra of initial
p -type
silicon samples with
=1 Ohm
cm (boron-doped silicon), doped with sulfur in
dark and under illumination (source is a conventional 2
V incandescent lamp)
under forward and reverse switching modes.
Photoconductivity measurements of samples doped with S were carried out
on IRS-21 spectrometer equipped with a cryostat, which allowed studying the
photoconductivity in a wide temperature range (
T =77–350
K ). To study only the
impurity-induced photoconductivity, a double filter system fabricated of a polished
single-crystal silicon plate was used, which was installed in front of the cryostat
window after IRS-21 lighting source.
An ohmic contact of InGa (97% -3%) was deposited on the front surface
with
p -type conductivity, and a contact made of InSn (52% -48%) was applied on
the back surface with
n -type conductivity. The sample appeared to be sensitive to
light.
Photoconductivity in dark conditions and under light were recorded
according to the standard diagram. The amperage were recorded with a SH300-
type universal nanoammeter.
Behavior of sulfur in silicon is characterized by the ionization energy
E i that
varies in a large diapason as reported by different authors [8].
The authors in [7] explain such an ambiguity in the values of the ionization
energy and the ionization energy band in the region
h
= 0.28–0.38
eV by the fact
that sulfur in silicon is a relatively shallow single-charged donor, and the formation
of deeper impurity levels can be associated with the fact that that sulfur relatively
easily forms associations of closely spaced singly charged atoms and the ionization
energies of electrons are determined not only by the ionization potential of an
isolated sulfur atom, but also by the Coulomb interaction of the ions included in
the association.