Electron mobilities in gallium, indium, and aluminum nitrides

Abstract

Electron mobilities in GaN and InN are calculated, by variational principle, as a function of temperature for carrier concentrations of 1016, 1017, and 1018 cm−3 with compensation ratio as a parameter. Both GaN and InN have maximum mobilities between 100 and 200 K, depending on the electron density and compensation ratio, with lower electron density peaking at lower temperature. This is due to the interplay of piezoelectric acoustic phonon scattering at low carrier concentrations and ionized impurity scattering at higher carrier concentrations. Above 200 K, polar mode optical phonon scattering is the mobility limiting process. The 300 and 77 K electron and Hall mobilities as functions of carrier concentration in the range of 1016–1020 cm−3 and compensation ratio are also calculated. The theoretical maximum mobilities in GaN and InN at 300 K are about 1000 and 4400 cm2 V−1 s−1, respectively, while at 77 K the limits are beyond 6000 and 30 000 cm2 V−1 s−1, respectively. We compare the results with experimental data and find reasonable correlation, but with evidence that structural imperfection and heavy compensation play important roles in the material presently available. Only phonon limited scattering processes are considered in the calculation of the mobility in AlN since it is an insulator of extremely low carrier concentration. We find a phonon limited electron mobility of about 300 cm2 V−1 s−1 at 300 K.

Growth of InN by vertical flow MOVPE

“…This smaller band gap is compatible with the main wavelength range of optical communication. Additionally, InN has excellent electron transport properties as predicted theoretically [2]. Combining high quality InN films with existing GaN technology would open new possibilities in the field of optical telecommunication and electronics.…”

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

“…[156] Electron mobilities in doped AlGaN layers approach hundreds of cm 2 V −1 s −1 , and are slightly higher in polarizationinduced 2DEGs. [54,66,157] Theoretically, electron and hole transport properties are likely to require fundamentally new concepts and approaches, because of the highly mismatched electronic properties of the binary constituents. For example, consider the AlInN material system.…”

Understanding the role of Si doping on surface charge and optical properties: Photoluminescence study of intrinsic and Si-doped InN nanowires

“…InN, after being discovered of a narrow bandgap (E g ∼ 0.65 − 1 eV) [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and predicted to possess the largest electron mobility among group-III nitrides (∼ 4400 cm 2 ·V −1 ·s −1 at 300 K), 15 has emerged as a highly promising material for infrared photodetectors and lasers, solar cells, ultrahigh-speed transistors, and sensors. [16][17][18] To date, however, the practical device applications of InN-based materials have been severely limited by the presence of extremely large residual electron density and the uncontrolled surface charge properties, as well as the difficulty in achieving p-type conductivity.…”