Stratulat Ana-Maria, Tantardini Christian, Azizi Maryam, Altalhi Tariq, Levchenko Sergey V, Yakobson Boris I
Skolkovo Innovation Center, Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, Moscow 143026, Russian Federation.
Hylleraas Center, Department of Chemistry, UiT The Arctic University of Norway, PO Box 6050 Langnes, N-9037 Tromsø, Norway.
J Phys Chem Lett. 2023 Oct 12;14(40):9118-9125. doi: 10.1021/acs.jpclett.3c02242. Epub 2023 Oct 4.
We propose the ZnVNbN alloy as a new promising material for optoelectronic applications, in particular for light-emitting diodes (LEDs). We perform accurate electronic-structure calculations of the alloy for several concentrations using density-functional theory with meta-GGA exchange-correlation functional TB09. The band gap is found to vary between 2.2 and 2.9 eV with varying V/Nb concentration. This range is suitable for developing bright LEDs with tunable band gap as potential replacements for the more expensive GaInN systems. Effects of configurational disorder are taken into account by explicitly considering all possible distributions of the metal ions within the metal sublattice for the chosen supercells. We have evaluated the band gap's nonlinear behavior (bowing) with variation of V/Nb concentration for two possible scenarios: (i) only the structure with the lowest total energy is present at each concentration and (ii) the structure with minimum band gap is present at each concentration, which corresponds to experimental conditions when also metastable structures are presents. We found that the bowing is about twice larger in the latter case. However, in both cases, the bowing parameter is found to be lower than 1 eV, which is about twice smaller than that in the widely used GaInN alloy. Furthermore, we found that both crystal volume changes due to alloying and local effects (atomic relaxation and the V-N/Nb-N bonding difference) have important contributions to the band gap bowing in ZnVNbN.
我们提出ZnVNbN合金是一种用于光电子应用，特别是发光二极管（LED）的新型有前景的材料。我们使用具有元广义梯度近似（meta-GGA）交换关联泛函TB09的密度泛函理论，对几种浓度的该合金进行了精确的电子结构计算。发现带隙随V/Nb浓度的变化在2.2至2.9电子伏特之间。这个范围适合开发具有可调带隙的明亮LED，作为更昂贵的GaInN系统的潜在替代品。通过明确考虑所选超晶胞中金属亚晶格内金属离子的所有可能分布，考虑了构型无序的影响。我们针对两种可能的情况评估了带隙随V/Nb浓度变化的非线性行为（弯曲）：（i）在每个浓度下仅存在总能量最低的结构，以及（ii）在每个浓度下存在带隙最小的结构，这对应于当也存在亚稳结构时的实验条件。我们发现后一种情况下的弯曲约为前一种情况的两倍。然而，在这两种情况下，弯曲参数都被发现低于1电子伏特，这比广泛使用的GaInN合金中的弯曲参数小约两倍。此外，我们发现合金化引起的晶体体积变化和局部效应（原子弛豫以及V-N/Nb-N键差异）对ZnVNbN中的带隙弯曲都有重要贡献。
