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Chapter 12: Problem 98

Indicate whether this statement is true or false: If you want a semiconductor that emits blue light, you could either use a material that has a band gap corresponding to the energy of a blue photon or you could use a material that has a smaller band gap but make an appropriately sized nanoparticle of the same material.

Short Answer

Expert verified
The statement is true. A semiconductor that emits blue light can be created in two ways: 1) using a material with a band gap corresponding to the energy of a blue photon, which follows standard semiconductor principles, and 2) using a material with a smaller band gap and producing an appropriately sized nanoparticle, which involves the quantum confinement effect to increase the band gap and achieve the desired blue light emission.

Step by step solution

01

Definition of Band Gap and Its Relation to Emitted Light

The band gap of a material refers to the energy difference between its valence band and conduction band. When electrons jump from the conduction band to the valence band, they release energy in the form of light (also called a photon). The energy of this emitted photon is equal to the band gap of the material. The color of the emitted light depends on the photon's energy, which is related to its wavelength (or frequency): blue light has higher energy than, for instance, red light.
02

Using a Material with a Band Gap Corresponding to Blue Light

To create a semiconductor that emits blue light, we must first find a material with a band gap that matches the energy of a blue photon. According to the energy-band relationship, an appropriate band gap would cause electrons in the conduction band to drop to the valence band, releasing blue light. This method is straightforward and in line with the principles of semiconductor science. Thus, this part of the statement is true.
03

Using Nanoparticles to Alter the Emitted Light

The second part of the statement deals with using materials with a smaller band gap and making a nanoparticle of a specific size to emit blue light. Indeed, the size of a nanoparticle can affect the energy levels of the material because of the quantum confinement effect. When the size of a particle is decreased, the band gap increases. This effect is more pronounced in semiconductor materials. By using a semiconductor material with a smaller band gap and creating an appropriately sized nanoparticle, we can effectively increase its band gap to achieve the desired emission of blue light. This part of the statement is also true.
04

Conclusion

The statement is true: A semiconductor that emits blue light can be achieved by either using a material with a band gap corresponding to the energy of a blue photon or by using a material with a smaller band gap and creating an appropriately sized nanoparticle. Both methods allow for the emission of blue light based on semiconductor principles and the quantum confinement effect.

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Most popular questions from this chapter

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