Gallium nitride (GaN) is an important commercial semiconductor for solid-state lighting applications. Atomically thin GaN, a recently synthesized two-dimensional material, is of particular interest because the extreme quantum confinement enables additional control of its light-emitting properties. We performed first-principles calculations based on density functional and many-body perturbation theory to investigate the electronic, optical, and excitonic properties of monolayer and bilayer two-dimensional (2D) GaN as a function of strain. Our results demonstrate that light emission from monolayer 2D GaN is blueshifted into the deep ultraviolet range, which is promising for sterilization and water-purification applications. Light emission from bilayer 2D GaN occurs at a similar wavelength to its bulk counterpart due to the cancellation of the effect of quantum confinement on the optical gap by the quantum-confined Stark shift. Polarized light emission at room temperature is possible via uniaxial in-plane strain, which is desirable for energy-efficient display applications. We compare the electronic and optical properties of freestanding two-dimensional GaN to atomically thin GaN wells embedded within AlN barriers in order to understand how the functional properties are influenced by the presence of barriers. Our results provide microscopic understanding of the electronic and optical characteristics of GaN at the few-layer regime.

中文翻译：

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第一性原理二维GaN的电子和光学性质

氮化镓（GaN）是用于固态照明应用的重要商业半导体。原子薄的GaN是一种最近合成的二维材料，因为它具有极端的量子限制，因此可以对其发光特性进行额外的控制，因此特别受到关注。我们基于密度泛函和多体扰动理论进行了第一性原理计算，以研究单层和双层二维（2D）GaN作为应变的函数的电子，光学和激子性质。我们的结果表明，单层2D GaN的发光蓝移到了深紫外范围，这有望用于灭菌和水净化应用。双层2D GaN的发光发生在与其体相类似的波长处，这是因为量子限制的Stark位移消除了量子限制对光学间隙的影响。通过单轴面内应变可以在室温下发出偏振光，这对于高能效的显示应用是理想的。我们将独立式二维GaN的电子和光学特性与嵌入AlN势垒的原子薄GaN阱进行了比较，以了解势垒如何影响功能特性。我们的结果从微观角度了解了GaN的电子和光学特性。通过单轴面内应变可以在室温下发出偏振光，这对于高能效的显示应用是理想的。我们将独立式二维GaN的电子和光学性能与嵌入AlN势垒的原子薄GaN阱进行了比较，以了解势垒如何影响功能特性。我们的结果从微观角度了解了GaN的电子和光学特性。通过单轴面内应变可以在室温下发出偏振光，这对于高能效的显示应用是理想的。我们将独立式二维GaN的电子和光学性能与嵌入AlN势垒的原子薄GaN阱进行了比较，以了解势垒如何影响功能特性。我们的结果从微观角度了解了GaN的电子和光学特性。