Electron mobility in ordered β -(AlxGa1−x)2O3 alloys from first-principles

Abstract

Alloying Ga2O3 with Al2O3 yields diverse structural phases with distinctive optoelectronic properties, making them promising candidates for ultrawide bandgap semiconductors in next-generation power electronics. Yet, there is a lack of sound knowledge of the carrier dynamics in the (AlxGa1−x)2O3 alloys due to their structural complexity. Herein, we focus on the ordered β-(AlxGa1−x)2O3 alloys, predict their carrier mobility, and determine the intrinsic electron mobility limit based on solving linearized Boltzmann transport equations from first principles. The predicted electron mobility for ordered β-(Al0.25Ga0.75)2O3 and β-(Al0.5Ga0.5)2O3 alloys at 300 K, respectively, is 103.6 and 80.60 cm2/V s, demonstrating excellent agreement with literature experiments. Such low electron mobility is limited by the intrinsically strong polar optical phonon (POP) scattering process. As the Al content further increases, the alloy's electron mobility further reduces mainly due to the enlarged Pauling ionicity, Fröhlich coupling constant, and POP scattering. This work provides physical insight into the carrier dynamics in ordered β-(AlxGa1−x)2O3 alloys and seeks to improve the electron mobility for potential applications in high-power electronics.

Nontrivial role of polar optical phonons in limiting electron mobility of two-dimensional Ga2O3 from first-principles

“…The electron energy is enhanced by increasing the concentration of ionized impurity, which dramatically increases the rate of electron-phonon collisions and leads to significantly reduced electron mobility, similar to the case of bulk b-Ga 2 O 3 . 55…”

Alloying enhanced negative Poisson's ratio in two-dimensional aluminum gallium nitride (AlxGa1−xN)

“…Generally, alloys can be categorized into ordered and disordered alloys, and our work focuses on ordered alloys. [26][27][28][29] Moreover, many two-dimensional alloys with a large percentage of doping have been successfully prepared experimentally in recent years. [30][31][32] Moreover, some methods also exist that can be used to enhance the performance of micro and nanodevices include constructing heterojunctions, 33 applying strain, 34 and so on.…”

Formation energy crossings in Ga2O3-Al2O3 quasibinary system: ordered structures and phase transitions in (Al x Ga1−x )2O3

“…In addition, the bandgap of Ga 2 O 3 can be tuned at a wide range using substitutional alloying on the Ga site by Group III elements. [6][7][8][9][10][11][12][13][14][15][16] For instance, it was shown theoretically that increasing the Al doping composition of Ga 2 O 3 linearly increases the bandgap of the semiconducting crystal. 6,7) On the other hand, In the case of In substitution, the bandgap decreases with increasing doping concentration.…”