| Summary: | Background. Despite the fact that InGaN / GaN-based structures have firmly
conquered the LED market, some issues remain unresolved about how the electrical
and optical characteristics of LEDs based on them change under the influence of external
factors: temperature, current, radiation, etc. Of greatest interest is the change
in the radiation intensity of the structure under the influence of external factors,
i.e. mechanism of emergence and evolution of nonradiative recombination channels.
The purpose of this work is to study the effect of γ-radiation on the volt-ampere
and ampere-brightness characteristics of structures with quantum wells based on
InGaN / GaN.
Materials and methods. To achieve this goal, the volt-ampere and amperebrightness
characteristics of the structure based on InGaN / GaN were measured
in the range of currents up to 30 mA at room temperature and radiation doses of
0–0.4 MRad. The measurements of the electrical and optical characteristics were
carried out in one cycle; when registering the ampere-brightness characteristic, the
output signal was the photocurrent of the reverse-biased photodiode. To analyze the
obtained volt-ampere characteristics, a generalized recombination model was used,
which makes it possible to describe the process of current transfer in a spatially disordered
structure, when tunneling is one of the stages of the process.
Results. The volt-ampere characteristics of InGaN / GaN-based structures are
analyzed at room temperature for γ-ray irradiation doses of 0–0.4 MRad. A significant
change in the volt-ampere characteristics under the action of irradiation in the
voltage range up to 3.1 V. A change in volt-ampere characteristics causes a change
in the dependences of the differential slope index β on voltage and d f (U )
dU
β = .
A change in the ampere-brightness characteristics is found, which is consistent with
the modification of the electrical properties under the action of irradiation with
γ-quanta.
Conclusions. In the voltage range at an irradiation dose of 0.2 MRad, a region
( )~ exp
r 2
I U eU
kT
is observed, which is associated with the decomposition of
Mg–H complexes, and hydrogen deactivation of the detected recombination center.
This hypothesis is confirmed by a change in the amplitude of the extremum on the
dependence d f (U)
dU
β = , which is used to determine the presence of recombination
centers in the structure under study, and the behavior of the ampere-brightness characteristics
with increasing sample irradiation dose.
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