Ga composition effects on the electrical parameters of (Al,Ga)Sb/InAs two-dimensional electron gas

Abstract

The effects of Ga composition on the electrical parameters of (Al,Ga)Sb/InAs two-dimensional electron gas have been investigated. The (Al,Ga)Sb/InAs structures are grown on GaAs (001) substrate by molecular-beam epitaxy with various Ga compositions in Al1−x Ga x Sb bottom barrier. The sheet resistance shows a crossover with the variation of temperature, and the temperature T* corresponding to this crossover decreases with increasing the Ga composition. The temperature dependence of the electron mobility is similar for the samples with different Ga compositions, while the temperature dependence of the carrier density is obviously different. Qualitative analyses reveal that the temperature dependent portion of carrier density is mainly determined by the interface-related donors. A thermal activation model is used to fit the temperature dependence of carrier density, and the fitting results imply that the thermal activation energies of the carriers are significantly affected by the Ga composition. Our results provide useful information for understanding the sources of carriers in the (Al,Ga)Sb/InAs systems, and provide one pathway for the modulation of the temperature dependent carrier density.

Electron mobility anisotropy in (Al,Ga)Sb/InAs two-dimensional electron gases epitaxied on GaAs (001) substrates

“…Based on this model, the PE scattering can be anisotropic owing to the different correlation lengths in the [−110] and [110] directions [22,29] . By comparing the magnitude of anisotropic electron mobility in samples A and B1, it can be inferred that the scattering from trenches has a greater impact on the electron mobility anisotropy than the PE scattering.…”

“…As revealed by many works, the anisotropic electron mobility in 2DEGs based on III-V semiconductors could be induced by the anisotropic morphology, which is further related to the anisotropy of lattice relaxation [20] or interface roughness [21] . However, in some cases, the electron mobility of 2DEGs with isotropic morphology is also anisotropic [22] . This suggests that there are other physical origins of the anisotropic electron mobility.…”