What Bandgap Energy Range is Required for Blue LEDs?

[aChordate]

Homework Statement

Blue light corresponds to free space wavelengths of approximately 450 to 495 nm. If we want to use a semiconductor to make a blue LED, what range of energies must the semiconductor's bandgap fall within? Express your answer in units of electron volts(eV). What is an example of a real semiconductor with a bandgap in this range?

Homework Equations

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The Attempt at a Solution

Can someone lead me in the right direction? From what I've read, blue light LED are high energy and the whole notion of bandgap energies confuses me.

 

[CWatters]

Relevant Equations..

Frequency = velocity * wavelength
Energy = Planck const * frequency

 

[ehild]

Relevant Equations..

Frequency = velocity * wavelength

Frequency = speed / wavelength

ehild

 

[CWatters]

Oops yes that's right.

Velocity = frequency * wavelength
so
frequency = Velocity/wavelength

 

[Nickie]

I can provide some insight into this topic. The bandgap energy is a fundamental property of a semiconductor material that determines the energy required for an electron to move from the valence band to the conduction band, creating a free electron and a positively charged hole. In order to emit blue light, the bandgap energy of a semiconductor material needs to be in the range of approximately 2.48 to 2.76 eV. This range corresponds to the energy of photons with wavelengths between 450 to 495 nm, as mentioned in the homework statement.

One example of a real semiconductor material with a bandgap in this range is gallium nitride (GaN), which has a bandgap energy of 3.4 eV. By adding certain impurities, such as indium or aluminum, the bandgap energy of GaN can be reduced to the desired range for blue light emission. This is the basis for the production of blue LEDs, which are widely used in electronic devices and lighting applications.

Understanding the bandgap energy of a semiconductor is crucial for designing and producing efficient LEDs of different colors, as well as other electronic devices. I recommend further research on this topic to gain a deeper understanding of bandgap energies and their role in semiconductor materials.