What are semiconductors?
Semiconductors are materials whose electrical conductivity lies between that of conductors (e.g., copper) and insulators (e.g., glass). They play a central role in modern electronics. Semiconductors differ from other materials in one important detail. Normally, materials can be classified into one of two categories: either they conduct electricity or they do not. Metals, for example, conduct electricity, while insulators do not. Semiconductors fall exactly in between.
Semiconductors do not conduct electricity as well as metals, but they also do not block it completely like insulators. Therefore, they occupy an important position between these two extremes. The conductivity of a semiconductor—that is, how much current can actually flow—depends on various factors: temperature, doping, and the applied voltage.
A Comparison of the Most Important Semiconductor Materials
| Material | Type | Features | Typical Application | Status |
|---|---|---|---|---|
| Silicon (Si) | Inorganic semiconductors | Stable, cost-effective, widely used, easy to work with | Transistors, microchips, solar cells, diodes | Predominant Material |
| Germanium (Ge) | Inorganic semiconductors | Higher charge carrier mobility than Si, more temperature-sensitive | Early transistors, special high-frequency applications | Largely replaced by silicon |
| Gallium arsenide (GaAs) | Compound Semiconductor | High electron mobility, direct bandgap | High-frequency transistors, laser diodes, cellular communications | Specialty Markets |
| Gallium nitride (GaN) | Compound Semiconductor | High breakdown voltage, efficient at high temperatures | LEDs (blue lights), power electronics, 5G systems | Growing, Future Technology |
| Silicon carbide (SiC) | Compound Semiconductor | High thermal stability, high breakdown strength | Electric vehicles, rail propulsion systems, wind energy | Rapidly growing |
| Indium phosphide (InP) | Compound Semiconductor | High electron mobility, efficient light emission | Telecommunications, Fiber-Optic Technology, Infrared Lasers | niche market |
Semiconductors are usually made of silicon or germanium. The structure of their atoms allows them to form crystal lattices, which, together with their electrons, provide electrical conductivity. Silicon is by far the most widely used material, as it is characterized by low manufacturing costs and very stable properties. Germanium was particularly important in the early days of semiconductor technology, but has since been largely replaced by silicon and is now used only in specific applications. Compound semiconductors such as gallium nitride, gallium arsenide, and indium phosphide are used in applications where silicon, with its physical properties, does not provide an adequate solution—for example, in optoelectronics.
What are the properties of semiconductors?
Semiconductors have several distinctive properties that set them apart from conductors and insulators and make them ideal for a wide range of applications in electronics.
1. Bandgap
The band gap—also known as the energy band gap—is a flexible region through which no current flows. The width of this gap depends on the specific semiconductor material. Metals have no band gap at all, while the band gap in insulators is very large. In semiconductors, it lies somewhere in between and can be specifically controlled—this is the crucial difference that makes them so valuable for electronics.
2. Endowment
Doping consists of impurity atoms that are specifically added to the semiconductor material to control its conductivity. This results in two basic types:
- n-type semiconductor: Contain additional free electrons (negative charge carriers). Typical dopants for silicon: phosphorus or arsenic.
- p-type semiconductor: They contain so-called "holes," i.e., missing electrons (positive charge carriers). A typical dopant for silicon is boron.
Doping not only allows conductivity to be controlled—it also enables the creation of pn junctions, which are of fundamental importance for electronic components such as diodes and transistors.
3. Load carriers
Charge carriers—either electrons or holes—give semiconductor components their electrical conductivity. Pure, undoped semiconductors have very few free charge carriers at room temperature. Their electrical conductivity is therefore low under normal conditions. As the temperature rises, additional charge carriers are released, which increases conductivity.
4. Temperature Dependence
The electrical conductivity of semiconductors is significantly influenced by the ambient temperature. Thermal energy releases more charge carriers, causing conductivity to increase as the temperature rises. This behavior is the exact opposite of that of metals, whose conductivity decreases at higher temperatures. For technical applications, this means that a semiconductor’s temperature characteristics are a decisive factor in determining the areas in which it can be used.
| Property | Conductor (e.g., copper) | Semiconductors (e.g., silicon) | Insulator (e.g., glass) |
|---|---|---|---|
| Band gap | None | Small to medium (0.1–3 eV) | Very large (> 5 eV) |
| Conductivity at 20 °C | Very high | Low to moderate, controllable | Nearly zero |
| Temperature Behavior | Conductivity decreases with heating | Conductivity increases with heating | Hardly changeable |
| Is doping possible? | No (pointless) | Yes – can be controlled precisely | No |
| Control of Conductivity | Not controllable | High – due to doping, temperature, voltage | Not controllable |
| Typical Application | Cables, Windings, Rails | Transistors, diodes, microchips, LEDs | Housings, Separating Layers, Encapsulants |
What are the applications of semiconductors?
Semiconductors are among the most important materials in modern electronics. They are used to manufacture diodes, transistors, integrated circuits, and many other components. These components form the basis for nearly all electronic devices and systems in today’s technological world.
Transistors—the Heart of Digital Electronics
Transistors are one of the most important products manufactured using semiconductors. They perform two key functions in electronics:
- Signal gain: Transistors pick up weak electrical signals and amplify them to usable levels—the basic principle behind audio amplifiers, radio transmitters, and measurement technology.
- Switching function: As electronic switches, transistors turn electrical signals on or off—this is the basis of all digital circuit technology (0 and 1). In addition, transistors can withstand high currents and voltages, making it possible to efficiently control power in systems.
Integrated Circuits and Microchips
Thanks to the properties of semiconductors, it is possible to manufacture integrated circuits and microchips. Semiconductors make it possible to integrate a large number of transistors onto a single chip—along with other electronic components. This makes it possible to continuously increase the computing power and storage capacity of computers and to implement complex circuits in the smallest of spaces. Without this miniaturization, neither the smartphone nor the modern automobile would be conceivable.
Optoelectronics: LEDs, Laser Diodes, and Photovoltaics
Semiconductors are also used in LEDs, photovoltaics, and laser diodes. The structure and composition of the semiconductor determine the wavelength of the light produced. In solar cells and photovoltaics, on the other hand, semiconductors enable the generation of electricity from sunlight—an area of application that has grown significantly in importance in recent years.
Sensors
Semiconductors are also used in sensor technology and enable the measurement of temperature, light, and pressure. Because their electrical conductivity changes depending on the ambient temperature, temperature values can be measured with precision. The change in conductivity under mechanical pressure enables pressure measurement. By converting light into electricity, light sensors determine how much light surrounds the sensor.
| Scope of Application | Component | Semiconductor material | Example |
|---|---|---|---|
| Digital Electronics | Transistor, logic gate, microcontroller | Silicon | CPU, control units, PLCs |
| Data Storage | Flash memory, DRAM | Silicon | USB flash drive, RAM, SSD |
| Energy Conversion | Solar cell, power diode, IGBT | Silicon, SiC | Photovoltaic system, frequency converter |
| Light Generation | LED, laser diode | GaN, GaAs, InP | LED lighting, laser scanners, data transfer |
| Communication | RF transistor, mixer | GaAs, GaN | Mobile Communications, Radar, 5G Infrastructure |
| Sensors | Temperature sensor, pressure sensor, photodiode | Silicon | Industrial sensors, automotive control units, medical technology |
| Power Electronics | MOSFET, IGBT, thyristor | Silicon, SiC, GaN | Electric Drives, Charging Infrastructure, Welding Technology |
Semiconductors, Microtechnology, and the Role of the Electrician
Semiconductors are a key area of focus for Electrician in modern industry. They are involved in the manufacture of semiconductors and the resulting components for microtechnology and sensor technology. Their responsibilities also include integrating the individual components into complete systems, configuring them, equipping them with the appropriate software, and delivering them to customers.
As semiconductor technology becomes increasingly widespread across all industries—from the automotive industry to energy technology and medical technology—the demand for qualified electricians who can work with these systems is also growing. In manufacturing, maintenance, and plant engineering, skilled workers with expertise in electronics and semiconductor technology are in particularly high demand.
Typical Duties of Electricians in the Semiconductor Industry
- Installation and Wiring: Installation of semiconductor-based control units, frequency converters, power electronics, and sensor systems in machines and equipment.
- Commissioning: Setup, configuration, and testing of electronic control systems, programmable logic controllers (PLCs), and control systems.
- Troubleshooting and Maintenance: Identifying and correcting errors in electronic systems; replacing defective semiconductor components.
- Quality Assurance: Testing and documentation of electronic assemblies in accordance with standards—such as DIN EN 61010 or IEC standards.
- System Integration: Assembling individual components into fully functional systems, including software installation and customer training.
Skills Shortage in Electrical Engineering and Semiconductor Technology
The semiconductor industry and the electrical engineering sector in Germany are suffering from a severe shortage of skilled workers. Companies in the fields of microtechnology, sensor technology, automation technology, and power electronics are desperately seeking qualified electricians and electronics engineers. Temporary staffing from Eastern Europe offers a quick and legally compliant solution here: Qualified electricians from Poland, Slovakia, or Lithuania are EU citizens and can be deployed in Germany without a work permit or visa process—and are typically ready to start work within 7–10 business days.
Frequently Asked Questions About Semiconductors
The difference lies in electrical conductivity and the size of the band gap. Conductors such as copper or aluminum have no band gap—electrons can move freely, and current flows easily. Insulators such as glass or ceramics have a very large band gap—electrons cannot cross the gap, so no current flows. Semiconductors fall somewhere in between: Their bandgap is small enough that conductivity can be controlled through specific measures (doping, temperature, voltage)—so they can either conduct or block current depending on how they are controlled.
Silicon is the second most abundant element in the Earth's crust (after oxygen) and is therefore very inexpensive and available in large quantities. It can be produced in a very high-purity form, is chemically stable up to about 150 °C, has suitable electrical properties (bandgap of approximately 1.1 eV), and can be precisely controlled through doping. In addition, a natural oxide layer (SiO₂) can form on silicon surfaces, which serves as an excellent insulator—a crucial advantage for chip manufacturing.
Doping refers to the controlled introduction of impurity atoms into a semiconductor material to alter its electrical conductivity. In n-type materials, atoms with more valence electrons are introduced (e.g., phosphorus in silicon), which provide free electrons. In the p-type, atoms with fewer valence electrons are introduced (e.g., boron in silicon), which create so-called holes—missing electrons. The combination of n- and p-doped regions creates pn junctions, which form the basis for diodes and transistors.
Semiconductors are found in nearly every modern device. Smartphones, laptops, and tablets contain millions of transistors on a single chip. Household appliances such as washing machines and refrigerators are controlled by semiconductor-based microcontrollers. Electric cars use power semiconductors (SiC, GaN) in their drive systems and charging electronics. LED lighting is based on gallium nitride semiconductors. Photovoltaic systems convert light into electricity using silicon semiconductors. And in industry, semiconductor-based PLC systems control machines and production lines.
Electricians working in the semiconductor and electronics fields need, in addition to basic technical skills, an understanding of electronic components, circuit design, and measurement technology. It is important to be proficient in using oscilloscopes, multimeters, and test equipment; to have knowledge of PLC programming (e.g., Siemens S7); to be able to read circuit diagrams according to IEC standards; and, ideally, to have basic knowledge of troubleshooting electronic assemblies. This combination is in particularly high demand in the market and justifies higher hourly rates compared to electricians who specialize solely in installation work.
Silicon carbide (SiC) and gallium nitride (GaN) are playing an increasingly important role in electric mobility. SiC transistors are primarily used in inverters, onboard chargers, and DC/DC converters because they operate more efficiently at high voltages (400 V, 800 V systems) and high temperatures than conventional silicon IGBTs. GaN is primarily used in fast chargers and high-frequency applications. Both materials enable smaller, lighter, and more efficient power electronics—a crucial factor for the range and charging time of electric vehicles.