The molecular structure of a material has a significant impact during silicon manufacturing. On a molecular level, the distance between atoms within different solid materials or compounds determines their specific electrical properties.
This is crucial in selecting materials for applications such as high-performance optoelectronics or digital computing transistors. To help you understand which material is better for your project, here’s a detailed explanation of band gap in semiconductors.
For semiconductors, the energy differential between the bottom of the conduction band and the top of the valence band is known as the band gap. This energy is needed to move an electron from the valence band to the conduction band. This excitation occurs when energy, such as heat, light, or electrical energy, is applied.
The electron hole in the valence band and the resulting conduction-band electron are free to travel throughout the crystal lattice and act as charge carriers to carry electric current.
Since no states are available when the valence band is full, and the conduction band is empty, electrons cannot move within the solid. Because there is no net charge carrier mobility, no current is produced. However, the current can still flow if some electrons shift from the primarily full valence band to the mostly empty conduction band.
Each solid material has a unique energy-band structure. This variation in band structure causes a wide range of electrical properties in different materials.
Semiconductors are essentially defined as insulators with a band gap energy of less than 3.0 eV (~290 kJ/mol). This cutoff was selected because the conductivity of undoped semiconductors is extremely low at 3.0 eV and decreases exponentially with the band gap energy.
Furthermore, substances with larger band gaps (such as SrTiO3, Egap = 3.2 eV) do not absorb light in the visible spectrum.
A material's band gap plays a major role in determining its electrical conductivity. The gap size can affect the material's properties and behavior in a transistor. Small band gaps, sometimes called "narrow" band gaps, are found in semiconductors, whereas large band gaps, sometimes called "wide" band gaps, are generally found in insulators.
Additionally, the gap is manipulable and the subject of ongoing research.
These materials typically have a bandgap of less than 1 eV. Examples include silicon (Si) and germanium (Ge). Because their bandgap is small, they can be easily excited at room temperature, making them suitable for applications requiring efficient electron mobility, such as standard transistors and diodes.
However, their sensitivity to thermal noise can limit performance in high-temperature environments.
In contrast, wide bandgap semiconductors have a bandgap greater than 2 eV. Gallium nitride (GaN) and silicon carbide (SiC) are common examples. These elements are very strong compared with silicon and require three times the energy to allow an electron to start to move freely in the material.
This larger energy gap (or wider bandgap) gives these materials superior qualities, which makes them ideal for high-power applications, including power electronics and RF devices.
Some of these performance characteristics include:
Bandgap properties may change depending on the material's formation process. In grown materials, band gap and emission characteristics can be adjusted by controlling the strain in the deposited film using the substrate's thermal expansion coefficient.
Many structural and electrical properties of silicon, germanium, and conventional III-V and II-VI semiconductors are similar. Therefore, without significantly altering the overall integration scheme, materials scientists can adjust the semiconductor composition to tune the bandgap, lattice parameters, and other properties.
On the other hand, two-dimensional semiconductors originate from distinct regions of the periodic table. They differ in their chemical composition, lattice structures, and electrical characteristics.
Choosing between semiconductors with a wide or narrow bandgap frequently depends on the demands of the particular application:
Semiconductors are the foundation of contemporary electronics, allowing gadgets like solar cells, computers, and smartphones to function. A semiconductor's bandgap is a crucial feature that determines its performance and influences the properties and uses of a material.
Finding a wafer with the characteristics you need for your project is key to ensuring efficiency, durability, and optimal performance. If you need assistance selecting the right wafer for your project, contact Wafer World today!
