Januar
Bild des Monats Januar 2024
Ab initio calculation of electronic properties in random alloy semiconductors
For new applications such as microLED, it is desired to cover the whole visible spectrum from red over green to blue with devices based on a single material system. For cubic rock-salt (rs) Al1-xScxN (with 0 ≤ x ≤ 1) the band gap can be tuned between 1.4 eV in rs-ScN and 7.1 eV in rs-AlN.
The theoretical calculation of the electronic properties of such random alloy system with state-of-the-art density functional theory (DFT) poses multiple challenges:
The first challenge is the correct calculation of the band-gap. Despite the existence of many semi-empirical approaches to overcome the self-interaction-error in the DFT, we are able to calculate the band-gap completely from first principles applying the low-cost quasi-particle LDA-1/2 approach.
The second challenge is the description of the random alloy. The coherent potential approximation (CPA) enables the calculation of the system at any given composition. Furthermore, the CPA provides the Bloch spectral function (BSF), a k-resolved density of states which resembles a band structure for mixed alloys. The picture displays the BSF at various compositions.
Dieses Bild wurde eingereicht von Jan M. Waack (AG Prof. Dr. Christian Heiliger).
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