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Issue 16(51), Volume 1 | ISSN 3030-377X | 30.06.2025
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INTERNATIONAL SCIENTIFIC JOURNAL
ELECTROPHYSICAL PROPERTIES OF P-N JUNCTION DIODES UNDER
LIGHT AND DEFORMATION EFFECTS
Abdurakhmanova Shokhsanam Iqboljon kizi
Master
’
s student of Namangan State University
Abstract:
P-N junction diodes are one of the main elements of semiconductor
devices, and their electrophysical properties can change under optical and mechanical
influences. This study analyzes the changes in the conductivity, reverse current,
barrier potential and capacitance properties of P-N diodes under the influence of light
(photoelectric effect) and deformation (piezoeffect).
Keywords
: P-N junction diode, Photoelectric effect, Piezoelectric effect
(piezoeffect) Photocurrent, Spectral sensitivity, Direct and inverse piezoeffect,
Crystal lattice deformation, Opto-mechanical interaction, Semiconductor
conductivity, Barrier potential, Piezoresistive effect, Flexible electronics, Smart
sensors.
1. Photoelectric Effect Under the Influence of Light
- Photogeneration: Light quanta (photons) create electron-hole pairs at the P-N
junction, which causes a photocurrent.
- Spectral sensitivity: The response of the diode depends on the wavelength of
the incident light (for example, infrared or visible range).
- Applications: Solar cells, photodiodes, optical sensors.
Experimental Results:
- The photocurrent increases linearly with increasing light intensity.
- When the light frequency reaches the "red limit" of the P-N junction (for
example, ~1.1 eV for Si), the photocurrent ceases to be generated.
2. Deformation-Induced Piezoeffect
Piezoelectric effect (piezoeffect) is the interaction between mechanical
deformation and an electric field. This phenomenon is divided into two types:
1. Direct piezoeffect - the appearance of an electric potential in a material under
the influence of mechanical pressure
2. Inverse piezoeffect - the change in the shape of a material under the influence
of an electric field
Mechanism of the piezoelectric effect under deformation
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The piezoelectric effect is observed only in crystals that do not have a center of
symmetry. Main reasons:
- The emergence of an electric dipole moment as a result of the displacement of
ions
- Asymmetric structure of the crystal lattice
- Polarization of the crystal under the influence of external forces
The strongest piezoelectric effect is observed in the following materials:
- Quartz
- Tourmaline
- Barium titanate
(BaTiO₃)
- Lead zirconate-titanate (PZT)
Direct piezoelectric effect:
P =
d·σ
where:
P - polarization vector
d - piezoelectric modulus
σ
- mechanical stress
Inverse piezoelectric effect:
ε
=
d·E
where:
ε
- deformation
E - electric field strength
Important areas of application of the piezoelectric effect:
1. Sensors (pressure, vibration, sound sensors)
2. Actuators (precise actuators)
3. Energy storage (generation of electricity during walking)
4. Medicine (ultrasound devices)
5. Electronics (clock generators, filters)
- Crystal lattice distortion: Mechanical stress breaks the symmetry of the crystal
structure, resulting in the appearance of an electric field.
- Conductivity change: Stretching or compression shifts the energy bands of
semiconductors at the P-N junction.
- Experimental Results:
- Small deformations (<1%) increase the conductivity of the diode.
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INTERNATIONAL SCIENTIFIC JOURNAL
- Large deformations (>5%) cause crystal defects, which can dramatically
increase the reverse current.
- 3. Opto-Mechanical Interaction
- Hybrid effects: If a diode is simultaneously exposed to light and deformation, a
superposition of photocurrent and piezocurrent is observed.
- Applications:
- Smart sensors: Devices that measure light and pressure simultaneously.
- Flexible electronics: P-N diodes mounted on plastic substrates.
- 4. Theoretical Modeling
The following equations are used to understand the opto-mechanical response of
the P-N junction:
1. Photocurrent formula:
𝐼
𝑝ℎ
=
q*η*Φ*[1
-
𝑒
𝛼𝑑
)]Where:
-
η
- quantum efficiency,
-
Φ
- photon flux,
-
α
- absorption coefficient.
2. Piezoresistive effect:
∆R⁄R
=π∙σ
Where
π
- piezoresistive coefficient,
σ
- mechanical stress.
5. Conclusion and Future Research
Conclusion:
- Photocurrent can be generated in P-N diodes under the influence of light, and
piezocurrent under the influence of deformation.
- These effects can be used in optoelectronics and sensor technologies.
Future Directions:
- Materials optimization: New semiconductors with high photosensitivity and
flexibility (e.g. perovskites or organic diodes).
- Miniaturization: Study of opto-mechanical effects in nanoscale P-N junctions.
- Biomedicine: Implantable sensors using flexible P-N diodes.
References:
1. Streetman, B.G., Banerjee, S. (2016). *Solid State Electronic Devices* (7th
ed.). Pearson. Basic principles of P-N junctions, static and dynamic properties of
diodes.
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2. Sze, S.M., Ng, K.K. (2006). *Physics of Semiconductor Devices* (3rd ed.).
Wiley. The photoelectric effect under the influence of light and the effect of
deformation on the crystal lattice.
3. Saparov, B. (2010). *Physics of semiconductors*. Tashkent: Uzbekistan
Publishing House. Local sources on the optical and mechanical sensitivity of P-N
junctions.
4. Wikipedia - "Light" (2024).
5. "Light dispersion" - Fayllar.org.
6. "Piezoeffect" - Scientific articles (2023).
