Question

For each of the following pairs of semiconductors, which one will have the larger band gap: (a) InP or InAs (b) Ge or AlP (c) AgI or CdTe?

Short answer

Based on the given pairs of semiconductors and their band gap values, the larger band gaps are found in (a) InP with a band gap of 1.35 eV, (b) AlP with a band gap of 2.45 eV, and (c) AgI with a band gap of 2.90 eV.

Step-by-step solution

(a) InP or InAs: Lookup Band Gaps

To compare the band gap of InP and InAs, we first need to look up their band gap values. The band gap for InP is approximately 1.35 eV, and for InAs, it is about 0.36 eV.

(a) InP or InAs: Compare Band Gaps

Since the band gap for InP (1.35 eV) is larger than the band gap of InAs (0.36 eV), InP has the larger band gap of the two semiconductors.

(b) Ge or AlP: Lookup Band Gaps

To compare the band gap of Ge and AlP, we first need to look up their band gap values. The band gap for Ge is approximately 0.66 eV, and for AlP, it is about 2.45 eV.

(b) Ge or AlP: Compare Band Gaps

Since the band gap for AlP (2.45 eV) is larger than the band gap of Ge (0.66 eV), AlP has the larger band gap of the two semiconductors.

(c) AgI or CdTe: Lookup Band Gaps

To compare the band gap of AgI and CdTe, we first need to look up their band gap values. The band gap for AgI is approximately 2.90 eV, and for CdTe, it is about 1.44 eV.

(c) AgI or CdTe: Compare Band Gaps

Since the band gap for AgI (2.90 eV) is larger than the band gap of CdTe (1.44 eV), AgI has the larger band gap of the two semiconductors.

Key concepts

semiconductors

Semiconductors are essential materials used in a variety of electronic devices. They have properties between those of conductors and insulators, making them unique materials for controlling electrical current. A significant feature of semiconductors is their band gap. This is the energy difference between the valence band, where electrons are present, and the conduction band, where electrons can move freely to conduct electricity. Understanding the band gap is crucial since it determines the electrical conductivity of the material. Semiconductors are widely used in modern electronic gadgets like computers, smartphones, and solar panels due to their adaptability and efficiency.

indium phosphide (InP)

Indium Phosphide (InP) is a type of semiconductor that is often used in high-frequency and high-power electronics. With a band gap of approximately 1.35 eV, InP is known for its high electron velocity.
This property is beneficial for various applications such as fiber optic communication and photonic devices.

• InP is less affected by radiation, making it ideal for space applications.
• It also features thermal stability, adding to its utility in temperature-variable environments.

Indium Phosphide's optimal band gap makes it suitable for optoelectronics applications, including light detectors and lasers operating in the infrared spectrum.

indium arsenide (InAs)

Indium Arsenide (InAs) is another semiconductor material with different properties compared to InP. It has a relatively small band gap of about 0.36 eV.
This lower band gap is advantageous for applications requiring low noise and high sensitivity at room temperature.
InAs is commonly used in infrared detectors and thermal imaging sensors.

• Due to its narrow band gap, InAs can efficiently detect and emit infrared light.
• It also allows the fabrication of high-speed electronic devices due to its superior electron mobility.

The specific properties of InAs make it a specialized choice in advanced technology settings.

germanium (Ge)

Germanium (Ge) is a well-known semiconductor material that played a vital role in the early development of transistors. It features a band gap of approximately 0.66 eV.
Though less commonly used than silicon in contemporary applications, germanium still finds usage in certain niches.

• Germanium diodes, for example, are valued for their high sensitivity and low voltage operation.
• It is also used in some fiber optics and infrared optics technologies.

Owing to its unique properties, germanium is used in applications where its characteristics provide significant advantages.

aluminum phosphide (AlP)

Aluminum Phosphide (AlP) is a semiconductor with an impressive band gap of approximately 2.45 eV. This large band gap lends itself to unique uses in electronic devices.
AlP is often used in optoelectronic applications where high thermal and chemical stability is required.

• It is used in LED technology due to its ability to emit blue and green light when activated.
• It serves as a potential material in high-power and high-temperature electronics.

The robust nature of Aluminum Phosphide makes it a valuable material in various advanced scientific applications.

silver iodide (AgI)

Silver Iodide (AgI) is notable for having a high band gap of approximately 2.90 eV. This large band gap implies that AgI is more similar to an insulator under standard conditions.
However, its compound nature lends to unique applications outside traditional semiconductors.

• AgI is prominently used in weather modification practices, such as cloud seeding to encourage precipitation.
• Additionally, it finds its use in photography as a light-sensitive material.

Although not a typical semiconductor like silicon or germanium, Silver Iodide exhibits specific properties that prove useful in specialized contexts.

cadmium telluride (CdTe)

Cadmium Telluride (CdTe) is a semiconductor with a band gap of about 1.44 eV, making it a valuable material for a variety of electronic applications.
It is predominantly utilized in solar cells due to its optimal band gap for sunlight absorption.

• CdTe solar panels are known for their high efficiency and lower cost compared to traditional silicon solar panels.
• It's also used in infrared detectors due to its appropriate band gap and electrical properties.

The unique features of CdTe make it a preferred choice for renewable energy solutions and advanced detection technologies.