how does band gap energy work? when dealing with voltages and color change from LEDs[depends on phosphorous percentage]
Band gap energy is an important concept in understanding the behavior of semiconductors, including LEDs (Light Emitting Diodes). The band gap energy refers to the energy difference between the valence band (the highest energy band containing electrons in a material at absolute zero) and the conduction band (the lowest energy band that can accommodate free-moving electrons).
In semiconductors, the band gap energy determines the energy levels at which electrons can exist within the material. When an electron absorbs energy greater than or equal to the band gap energy, it can be excited from the valence band to the conduction band, leaving behind a positively charged "hole" in the valence band.
Now, let's discuss how band gap energy relates to voltages and the color change in LEDs. LEDs typically consist of a semiconductor material, such as gallium arsenide (GaAs) or gallium nitride (GaN), with different band gap energies. The band gap energy of the semiconductor material determines the wavelength of light emitted by the LED and, therefore, its color.
When a forward voltage is applied to an LED, electrons and holes recombine at the interface of the p-type and n-type regions within the LED structure. This recombination process releases energy in the form of photons, which we perceive as light. The energy of the emitted light is related to the band gap energy of the semiconductor material. Lower band gap energies result in longer wavelengths (e.g., red light), while higher band gap energies produce shorter wavelengths (e.g., blue light).
To achieve different colors in LEDs, manufacturers alter the band gap energy by incorporating different impurities or elements into the semiconductor material. For example, adding phosphorus to gallium nitride can lower the band gap energy, leading to the emission of light in the green spectrum.
To summarize, the band gap energy of a semiconductor material determines the energy levels at which electrons can exist within the material. This, in turn, affects the wavelength of light emitted by LEDs when a forward voltage is applied. Altering the band gap energy through impurities or elements allows manufacturers to control the color emitted by LEDs.