Density Functional Theory Study of Polarization-Induced Electron Confinement by Dilute Boron Alloying in ε-Ga<sub>2</sub>O<sub>3</sub> Nanometer-Thick Film for High Electron Mobility Transistor
Yan Wang, Jiahe Cao, Yimin Liao, Chuang Zhang, Zhigao Xie, Hanzhao Song, Jierui Xue, Andeng Qu, Yew Hoong Wong, Zengxia Mei, Chee‐Keong Tan
Abstract
Density functional theory computations were utilized to quantify the polarization discontinuity of 1.8 μC/cm 2 in ε-(B 0.0625 Ga 0.9375 ) 2 O 3 /ε-Ga 2 O 3 heterostructure. The polarization effect was sufficient to generate a two-dimensional electron gas (2DEG) at the heterostructure interface without doping. The creation of 2DEG occurred when the BGaO layer thickness exceeded 17 nm, with its density exhibiting a logarithmic increase as the thickness was augmented. However, the trend plateaued when the thickness surpassed 80 nm with a carrier density of 8.17 × 10 12 cm –2 . Moreover, guided by Griffith’s theory and enthalpy calculations, the epitaxial layer could potentially be pseudomorphically grown up to 968 nm under growth conditions of 1000 K with dilute boron alloying. This design heralds the potential for creating a high electron mobility transistor based on ε-BGaO with an epitaxial layer just nanometers thick, well-suited for high-power and radio frequency applications.