For which of the material is the energy gap at room temperature least?

Explanation:

Energy Gap of Materials at Room Temperature

Definition: The energy gap, also known as the bandgap, is the energy difference between the valence band and the conduction band of a material. It is a fundamental property that determines the electronic and optical behavior of materials. At room temperature, the energy gap plays a crucial role in defining whether a material behaves as a conductor, semiconductor, or insulator.

Correct Option Analysis:

The correct option is:

Option 1: Si (Silicon)

Silicon is a widely studied and utilized semiconductor material, particularly in electronics and photovoltaic applications. Its energy gap at room temperature is approximately 1.12 eV, which is the lowest among the materials listed. This relatively small bandgap allows silicon to conduct electricity under certain conditions, making it an excellent choice for semiconductor devices.

Detailed Analysis:

The energy gap is a crucial parameter in determining a material's electrical conductivity and optical properties. Materials with a smaller energy gap, such as silicon, require less energy for electrons to transition from the valence band to the conduction band. This property makes silicon ideal for applications like transistors, diodes, and solar cells. Silicon's moderate bandgap allows for efficient functioning in ambient temperature conditions, balancing conductivity and control over electronic devices.

Silicon's widespread use in the electronics industry stems from its abundance, stability, and ease of doping to create p-type and n-type semiconductors. Furthermore, silicon's bandgap is suitable for visible and near-infrared light absorption, making it a key material in photovoltaic technology.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 2: GaAs (Gallium Arsenide)

Gallium arsenide is another semiconductor material with a higher energy gap of approximately 1.43 eV at room temperature. Due to this larger bandgap, GaAs exhibits superior performance in high-frequency and optoelectronic applications, such as lasers and LEDs. However, its energy gap is larger than that of silicon, making it less suitable for applications where lower energy gaps are required. Additionally, GaAs is less abundant and more expensive to produce compared to silicon.

Option 3: Diamond

Diamond is a material with an exceptionally high energy gap of approximately 5.5 eV. This large bandgap classifies diamond as an insulator, as the energy required for electrons to transition from the valence band to the conduction band is prohibitively high at room temperature. While diamond possesses excellent thermal conductivity and mechanical properties, its electronic applications are limited due to its insulating nature.

Option 4: CdS (Cadmium Sulfide)

Cadmium sulfide is a semiconductor with an energy gap of approximately 2.42 eV at room temperature. This larger bandgap makes CdS suitable for applications involving ultraviolet light absorption, such as photoresistors and solar cells. However, its energy gap is significantly higher than silicon, making it less effective for applications requiring efficient conduction at lower energy levels.

Conclusion:

Among the materials listed, silicon (Option 1) has the smallest energy gap at room temperature, making it the correct answer. Its moderate bandgap of 1.12 eV enables it to function efficiently as a semiconductor in various electronic and photovoltaic applications. The other materials, GaAs, diamond, and CdS, have larger energy gaps, making them less suitable for applications where a smaller energy gap is required. Understanding the energy gap is essential for selecting the appropriate material for specific electronic and optical applications.