The electrical conductivity of semiconductors is highly sensitive to temperature changes. Unlike metals, whose conductivity decreases with rising temperature due to increased atomic vibrations, semiconductors exhibit a fundamentally different behavior: their conductivity increases as temperature rises. This unique characteristic arises from the way semiconductors generate charge carriers (electrons and holes), which are responsible for conducting electricity.
What is Semiconductor Conductivity?
Semiconductor conductivity is the ability of a semiconductor material to conduct an electric current under the action of an electric field, and is expressed by the symbol σ (sigma), usually in units of Siemens per meter (S/m) or Siemens per centimeter (S/cm). It reflects the strength of the current passing through the material per unit length and per unit cross-sectional area.
- σ\sigmaσ: electrical conductivity
- qqq: elementary charge (about 1.6×10-191.6 \times 10^{-19}1.6×10-19 C)
- nnn: free electron concentration
- ppp: hole concentration
- μn,μp\mu_n, \mu_pμn ,μp: electron and hole mobility (mobility)
Basic Relationship Between Conductivity and Temperature
The conductivity (σ) of semiconductors increases significantly with increasing temperature, and the pattern of change can be approximated as:
Why does Conductivity Increase at Higher Temperatures?
For semiconductors:
At low temperatures, the electron energy is insufficient to cross the gap between the valence band and the conduction band, the conductivity is very poor;
When the temperature rises, more and more electrons get thermal energy to jump to the conduction band, while leaving holes in the valence band, the formation of the “electron – hole pairs”, the number of free carriers increased greatly, and the electrical conductivity is also significantly increased. The number of free carriers increases dramatically, and the conductivity increases significantly.
Contrary to metals: Metals lose their electrical conductivity at high temperatures due to an increase in electron scattering frequency caused by enhanced thermal vibrations of the atoms.
Two Types Of Semiconductors Affected By Temperature
Intrinsic Semiconductor:
Pure silicon (Si), germanium (Ge), etc., not doped with impurities. Its conductivity increases dramatically with temperature because the higher the temperature, the more “electron-hole pairs” are excited.
Impurity Semiconductor (Extrinsic):
Doped with either a donor (N-type) or receiver (P-type) impurity.
- Low temperature: impurity atoms are not fully ionized, few free carriers;
- medium temperature: impurities gradually ionized, carriers increase, conductivity increased;
- At high temperature: tends to intrinsic behavior, showing temperature characteristics similar to those of pure semiconductors.
How to Measure Conductivity in temperature?
For Liquids (water, electrolyte, etc.):
Conductivity meter (with temperature probe)
Apure EC/TDS composite electrode + controller, take a bottle of the liquid to be measured (e.g. tap water or NaCl solution), together with a thermostatic water bath (or a heated magnetic stirrer) to make the conductivity of the electrolyte change with temperature.
Measurement process:
- Measure the conductivity every 5°C rise (it is recommended to record the 10 to 60°C interval);
- Also record the actual temperature of the liquid;
- Record data: Organize into a temperature vs conductivity table or graph;
- Fitting the curve: to determine if there is a linear or exponential increase.
For Solid Materials (e.g. semiconductor wafers):
Four-Point Probe
Take silicon wafers, doped germanium wafers or thermal materials, install the four-probe system, place it on the heating table, with the probes in good contact with the sample.
Set the temperature step: e.g., measure every 10°C increase, and analyze the characteristic curve by corresponding the temperature to the electrical conductivity into a curve.
Effect of Low Temperature On Conductivity
| Material Type | Effect of Lower Temperature on Conductivity | Application Recommendation |
|---|---|---|
| Solution (Water/Electrolyte) | Conductivity decreases, increased measurement error | Use temperature compensation or convert to standard at 25°C |
| Semiconductor | Conductivity drops significantly | Analyze low-temperature characteristics or select special materials |
| Apure Products | Supports temperature compensation, suitable for 0–50°C | Stay within recommended range; special calibration needed beyond |
Table Of Effect of Low Temperature On Conductivity
Products Adapted to Low Temperatures
| Product Type | Recommended Features | Low-Temperature Compatibility |
|---|---|---|
| Conductivity Meter Probe | Automatic temperature compensation (e.g., NTC/PT1000) | ✅ Supports 0–50°C |
| Industrial Probe (e.g., CS-EC Series) | Anti-condensation and anti-freeze sensor design | ✅ Recommended for use above 0°C |
| On-Site Measurement | Use with temperature-calibrated water or convert to 25°C standard | ✅ Recommended with temperature correction factor (α) |
Table Of Products Adapted to Low Temperatures
Summary
The conductivity of semiconductors increases significantly with temperature, a behavior that stems from the fact that an increase in temperature excites more electrons to leapfrog from the valence band to the conduction band, producing more free carriers (electrons and holes). At low temperatures, the carriers are not sufficiently excited and the semiconductor tends to be an insulator; at high temperatures, it tends to approach the intrinsic behavior and the conductivity increases dramatically.
At Apure, our instruments provide stable, temperature-compensated readings, whether you are analyzing ultrapure water, evaluating a chemical process, or studying the behavior of semiconductors. In addition to this we offer a range of ph water quality monitoring, flow meters, pressure measurement, level measurement and ozone generators, feel free to contact the dedicated technical team to help you!