Abstract
GaN-based semiconductors are promising materials for solid-state optoelectronic applications. However, the strong internal electrostatic field (IEF) along the [0001] direction is a serious problem that harms the efficiency of lighting devices based on GaN-based semiconductors due to the quantum confined Stark effect. Here we theoretically predict a method, reducing the dimensions from bulk to two-dimensional (2D) structures, to fundamentally remove the IEF. After thinning the materials to several nanometers, the wurtzite configuration (with strong IEF) spontaneously transform to the haeckelite (4 | 8) configuration (without IEF) due to the more stable neutral surface in the 4 | 8 configuration. Meanwhile, the 4 | 8 configuration maintain optoelectronic properties comparable to or even better than those of the wurtzite configuration. By carefully analyzing the interaction between 2D GaN and different types of substrates (SiC and graphene), we not only provide clear physical insights for experimental results but also address a “thickness-controlled” vdW epitaxy scheme to experimentally realize the 4 | 8 configuration. We believe that the 4 | 8 configuration without IEF is a prospective material for diverse optoelectronic applications. In addition, we propose a point of view in engineering the properties of GaN-based semiconductors.
Highlights
GaN-based semiconductors are highlighted for their excellent properties, such as tunable and direct band gap, high thermal conductivity, and good chemical stability[1]
The dipole moment causes opposite bound polarization charges on the metal-polar [0001] and N-polar [000–1] surfaces, which leads to a strong internal electrostatic field (IEF) along the [0001] direction[13,14,15]
We theoretically demonstrated by first-principles calculations that in GaN-based semiconductors, the 4 | 8 configuration is more energetically favorable than the wurtzite configuration after reducing the dimensions from bulk to 2D structures
Summary
GaN-based semiconductors are highlighted for their excellent properties, such as tunable and direct band gap, high thermal conductivity, and good chemical stability[1]. We theoretically demonstrated by first-principles calculations that in GaN-based semiconductors, the 4 | 8 configuration is more energetically favorable than the wurtzite configuration after reducing the dimensions from bulk to 2D structures.
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