What is direct band gap?

What is direct band gap?

In semiconductor physics, the band gap of a semiconductor can be of two basic types, a direct band gap or an indirect band gap. The band gap is called “direct” if the crystal momentum of electrons and holes is the same in both the conduction band and the valence band; an electron can directly emit a photon.

How do you calculate direct band gap?

Direct bandgap can be estimated from the plotting of (ahv)^2 in Y axis and energy photon in the X- axis, the intercept of the straight line in X-axis is the direct bandgap.

What is the absorption coefficient?

The absorption coefficient determines how far into a material light of a particular wavelength can penetrate before it is absorbed. The absorption coefficient, α, in a variety of semiconductor materials at 300K as a function of the vacuum wavelength of light.

What is absorption coefficient explain how do you determine the absorption coefficient?

The absorption coefficient describes the intensity attenuation of the light passing through a material. It can be understood as the sum of the absorption cross-sections per unit volume of a material for an optical process [7].

What are the examples of direct band gap?

Examples for direct band gap semiconductor materials are gallium arsenide (GaAs), indium gallium arsenide (InGaAs), gallium nitride (GaN), aluminum nitride (AlN), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium tellurite (CdTe), zinc sulfide (ZnS), lead sulfide (PbS) and lead selenide (PbSe).

What is the unit of band gap?

Physical property constants of Si and main wide-band-gap semiconductors

Property Unit Si
Band gap eV 1.12
Electron mobility μe cm2/Vs 1400
Hole mobility μh 600
Electric breakdown field Ec V/cm 3.0×105

How is the band gap of a semiconductor calculated?

An absorption edge of semiconductors corresponds to the threshold of charge transition between the highest nearly filled band and the lowest nearly empty band. According to inter-band absorption theory, the film’s optical gap can be calculated according to [ [**]J. Tauc (Ed.).

Why are indirect band gaps more likely to be absorbed?

The absorption spectrum of an indirect band gap material usually depends more on temperature than that of a direct material, because at low temperatures there are fewer phonons, and therefore it is less likely that a photon and phonon can be simultaneously absorbed to create an indirect transition.

How to calculate the band gap, absorption and reflectance?

How to calculate the band-gap, absorption and reflectance of any materials like graphene, doped ZnO, TiO2, ZrO2, NiOx, etc. Which software can be used and how to select the parmeters? If any manual or video on Youtube, please help me. Thanks Join ResearchGate to ask questions, get input, and advance your work.

Which is an example of a direct bandgap material?

Examples of direct bandgap materials include amorphous silicon and some III-V materials such as InAs and GaAs. Indirect bandgap materials include crystalline silicon and Ge. Some III-V materials are indirect bandgap as well, for example AlSb.

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