First-Principles Studies of Two-Dimensional Gallium Nitride Systems

Two-dimensional gallium nitride (2D GaN) systems represent a frontier in semiconductor research, marrying the wide band gap and robust chemical stability of bulk GaN with the unique confinement and surface phenomena of atomically thin layers. First-principles approaches—chiefly based on density functional theory and related ab initio methods—have provided predictive insight into the structural phases, electronic band structures, and optical and mechanical responses of planar and non-planar 2D GaN. Various predicted allotropes include hexagonal honeycomb lattices, haeckelite arrangements of squares and octagons, and buckled monolayers, each exhibiting distinctive band gaps, charge distribution and dielectric screening. Computational studies have also elucidated the effects of strain, surface passivation and chemical functionalisation, demonstrating tunable band-gap engineering, ultralow work functions via alkali-metal adsorption and strong excitonic binding energies. These findings underpin potential applications in light-emitting diodes, high-frequency field-effect transistors, photovoltaics and field-emission devices. Concurrently, first-principles molecular dynamics and van der Waals-corrected simulations have shed light on atomic-scale growth mechanisms for GaN intercalation beneath graphene, guiding experimental synthesis strategies. Taken together, these theoretical advances chart a pathway towards controlled fabrication and integration of 2D GaN into next-generation optoelectronic and energy-harvesting technologies.

Research from Nature Portfolio

First-principles calculations have revealed that candidate haeckelite structures of 2D GaN, composed of alternating square and octagonal rings, are energetically stable and semiconducting. Band-structure analyses indicate indirect gaps sensitive to ring topology, while passivation with small molecules can induce transitions to direct-gap behaviour. A separate study generalised the growth of ultrathin III–V semiconductors, demonstrating that interfacial engineering promotes layer-by-layer epitaxy of GaN with controlled thickness and high crystallinity, leading to phonon shifts, band-gap modulation and enhanced second-harmonic generation. In addition, ab initio treatment of excitonic effects in GaN monolayers has quantified binding energies of several hundred meV and radiative lifetimes in the picosecond to nanosecond range, emphasising the promise of 2D GaN for efficient light emission and photovoltaic conversion under reduced dielectric screening.

First-Principles Studies of Two-Dimensional Gallium Nitride Systems publication trend

The graph below shows the total number of articles in first-principles studies of two-dimensional gallium nitride systems across all publications each year (not limited to Nature Index journals).

Technical terms

First-principles calculations: Computational techniques deriving material properties directly from fundamental physical laws without empirical parameters.

Density functional theory (DFT): A quantum mechanical framework for computing electronic structure via electron density functionals.

Haeckelite structure: A two-dimensional network featuring nonhexagonal rings, typically squares and octagons.

Monolayer: A single atomic layer of material, conferring unique surface-dominated properties.

Exciton: A bound electron–hole pair within a semiconductor, influencing optical absorption and emission.

Band gap: The energy difference between valence and conduction bands, dictating electronic and optical behaviour.

Buckling: A structural deformation in a 2D layer wherein atoms displace out of the nominal plane, affecting symmetry and electronic states.

References

1. Alkali-metal-adsorbed g-GaN monolayer: ultralow work functions and optical properties. Discover Nano (2018).
2. GaN Haeckelite Single-Layered Nanostructures: Monolayer and Nanotubes. Scientific Reports (2015).
3. Universal growth of ultra-thin III–V semiconductor single crystals. Nature Communications (2020).
4. Giant excitonic absorption and emission in two-dimensional group-III nitrides. Scientific Reports (2020).
5. 2D graphitic-like gallium nitride and other structural selectivity in confinement at the graphene/SiC interface. CrystEngComm (2023).
6. A first-principles theoretical study of the electronic and optical properties of twisted bilayer GaN structures. Journal of Computational Electronics (2020).