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What is direct inter-band transition?
A direct inter-band transition refers to the process in which an electron in a semiconductor or insulator transitions directly from a filled valence band to an empty conduction band without changing its momentum. This type of transition occurs when photons with energy equal to or greater than the band gap energy are absorbed, allowing the electron to gain the necessary energy to move to the higher energy conduction band. Direct inter-band transitions are crucial for the operation of optoelectronic devices like light-emitting diodes (LEDs) and solar cells.
The band gap of elements arranged in ascending order is?
The band gap of elements generally increases as you move from metals to semiconductors and then to insulators in the periodic table. Metals typically have no band gap, allowing for free electron movement, while semiconductors have a small band gap that enables controlled conductivity. Insulators possess a large band gap, preventing the flow of electrons under normal conditions. Thus, in ascending order, the band gap can be characterized as: metals (0 eV), semiconductors (typically 0.1 to 3 eV), and insulators (greater than 3 eV).
What is the energy band gap of barium titanate?
The energy band gap of barium titanate is approximately 3.2 electron volts (eV). This wide band gap makes barium titanate a good candidate for various applications in electronics and optoelectronics.
Why effective mass is infinite at the middle of the band gap?
It sounds like a math trick because the electron cannot exist in the middle of the band gap. The trick would be that it would take an infinite amount of energy to excite the electron to the middle of the band gap.
Energy Band gap value for calcium carbonate and barium carbonate?
The energy band gap value for calcium carbonate (CaCO3) is around 5.6 eV, while for barium carbonate (BaCO3) it is approximately 6.3 eV. These values indicate the amount of energy required to promote an electron from the valence band to the conduction band in the respective materials.
Titanium dioxide is direct band gap or indirect band gap material?
Yes it is. Most Sn (tin) materials as semiconductors are direct band gap materials. Silicon on the other hand is an indirect band gap material.
What are the difference between direct and indirect band gap materials?
In a direct band gap the electron only needs energy to jump to the conduction band. In an indirect band an electron needs energy and momentum to jump to the conduction band
What are the Characteristics of Direct and indirect band gap semiconductors?
Direct band semconductors are mostly for LEDs. Indirect band semiconductors like Si and Ge are conventional diodes.
Is silicon a direct band gap material?
Silicon is by all means an indirect band gap material.
Why is silicon not used in fabrication of LED?
Silicon is an indirect band gap semiconductor
Why do we mostly use indirect semiconductors?
The indirect band gap semiconductors like silicon and germanium are mostly used because they are elemental, plentiful, and easier to process than the direct band gap semiconductors which are alloys or compounds.
Why indirect band gap material is used for manufacturing LED's?
Optical sources like LEDs use direct band gap so that conduction band electorn can recombine directly with a hole in valence band .
What is the difference between direct and indirect energy?
The band gap represents the minimum energy difference between the top of the valence band and the bottom of the conduction band, However, the top of the valence band and the bottom of the conduction band are not generally at the same value of the electron momentum. In a direct band gap semiconductor, the top of the valence band and the bottom of the conduction band occur at the same value of momentum.In an indirect band gap semiconductor, the maximum energy of the valence band occurs at a different value of momentum to the minimum in the conduction band energy
What are applications of direct and indirect band gap?
direct band gap means in e-k diagram valance bands are exactly below covalance band,in this band electron falls from the conduction band to valance band directly without going to metastable state and in indirect band gap the band electron falls from the conduction band to valance band by first going through the metastable state
Why silicon is a indirect band gap material?
Silicon is considered an indirect band gap material because the maximum of its valence band and the minimum of its conduction band occur at different momentum values (k-values) in its crystal structure. This means that a direct transition of electrons from the valence band to the conduction band requires a change in momentum, which is not possible without the assistance of a phonon (a quantized mode of vibration). As a result, silicon is less efficient at absorbing and emitting light compared to direct band gap materials, which have their band extrema aligned in momentum space. This property is crucial for its applications in electronic devices rather than optoelectronic applications.
The gallium arsenide is prepared for laser action but silicon and germanium are not. explain why?
I think because GaAs has a direct band gap transition but Si and Ge has indirect band gap transition. Both silicon and germanium are opaque and thus cannot be used to make LASERs.
What are the indirect bandgap materials?
Some examples of indirect bandgap materials include silicon, germanium, and gallium arsenide. These materials have a bandgap structure in which electrons have different momentum in the conduction band compared to the valence band, making optical transitions less likely.
