The effects of size and strain on the electronic behavior of AlN/GaN heterojunction

The electronic behavior of AlN/GaN heterojunction is investigated at thicknesses of 1.2~4.2 nm and biaxial strain of -8%~8% based on density functional theory. The structural stability, charge distribution, electronic properties, and transport properties of the cells reveal the enhancing effects of size and strain. With the thickness decreases, the bandgap values of the cells, as low as -0.387 eV, confirm the transition in structural nature, while the individual atomic layers remain bandgaps of at least 0.3 eV in DOS. The carrier mobility enhances to 2×10¹² m²/V/s. The cell with 1.2 nm thickness is weakened by 50% due to the quantum confinement effect. Under compressive strain ranging from -8% to 0%, the characteristics of heterojunctions are enhanced by an order of magnitude, in contrast, under 0%~8% tensile strain, the cells decrease slightly but for 2L cells.

本研究基于密度泛函理论，对厚度在1.2至4.2纳米之间，并承受-8%至8%双轴应变的AlN/GaN异质结的电子行为进行了探究。通过对结构稳定性、电荷分布、电子性质和传输性质的细胞分析，揭示了尺寸和应变对性能的增强效应。随着厚度的减小，细胞的带隙值降至最低-0.387电子伏特，证实了结构性质的转变，而单个原子层在DOS中的带隙值至少保持在0.3电子伏特。载流子迁移率提升至2×10¹² m²/V/s。厚度为1.2纳米的细胞由于量子限域效应的影响，其强度减弱了50%。在-8%至0%的压缩应变范围内，异质结的特性提高了十倍，而相比之下，在0%至8%的拉伸应变范围内，细胞性能略有下降，但对于2L细胞则保持稳定。