An unprocessed, on-axis Si substrate has a single-layer atomic step structure on its surface. The epitaxial growth of III-V materials on substrates results in the high-energy planar defect called antiphase domain (APD). The APD reduces the minority carrier lifetime in devices, degrading the performance of devices. Placing an on-axis Si substrate in the hydrogen environment for high-temperature annealing can promote the transformation of single-layer atomic steps into double-layer atomic steps and suppress APD generation at the GaAs/Si interface. However, the molecular beam epitaxy (MBE) technology cannot take hydrogen as annealing environment. Existing experimental methods involve changing the experimental process, which is unique and difficult to reproduce, to promote the annihilation of APD in GaAs materials. However, the APD annihilation mechanism remains unclear. In this study, the formation energy of APD propagating along the {110}, {111}, and {112} planes in GaAs materials at different temperatures is calculated using the first principle to explore the APD annihilation mechanism. The most stable propagating plane of the APD changes from {110} to {112} when the temperature exceeds 660 K. A 1.4-μm thick GaAs epitaxial layer is grown on an on-axis Si (001) substrate using the MBE technology. The results demonstrate that the APD density on the GaAs surface decreases and the annihilation probability of the APD increases with an increase in the growth temperature. At high growth temperatures, the APD can easily be twisted to the {112} plane and annihilate.

Aiming at the phenomenon of APD kink and annihilation in on-axis GaAs/Si(001) epitaxial materials, this paper presents the detailed exploration and analysis of theoretical simulations and experiments, respectively. According to the different propagation planes of the APD in GaAs, APD models propagating along the {110}, {111}, and {112} planes are established. The APD formation energy on these three propagation surfaces and their variation trends with temperature are obtained using the first principle. Experimentally, GaAs epitaxial layer is grown on an on-axis Si (001) substrate based on the MBE technology using a three-step method. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) are used to characterize the surfaces and cross sections of the samples.

The APD formation energy on different propagation planes varies with temperatures. At 0-660 K, the APD formation energy on the {110} propagation plane is the lowest, and at 660-1500 K, the APD formation energy on the {112} propagation plane is the lowest (Fig. 3). In the range of 450-600 ℃, the higher the growth temperature, the lower the APD density (Fig. 5) and the higher the APD annihilation degree in the sample (Fig. 6), which is consistent with the calculated results.

In this study, the formation energy of APDs propagating along the {110}, {111}, and {112} planes in GaAs is calculated based on the first principle, and the effect of growth temperature on the APD formation energy in vacuum environment is determined. The theoretical results demonstrate that, at 0 K, the formation energy of the APD propagating along the {110} plane is the lowest; in the temperature range of 0-660 K, the formation energy of the APD propagating along the {110} plane is the lowest; and in the temperature range of 660-1500 K, the APD propagating along the {112} plane has the lowest formation energy. The experimental results demonstrate that when the temperature increases from 450 ℃ to 600 ℃, the APD density decreases by 42%, and in the sample with a growth temperature of 500 ℃, more APDs along the {112} plane are found to meet other APDs and annihilate. A higher growth temperature promotes the kink of the APD to the {112} plane and then the APD annihilates in the GaAs material with a certain thickness, which is consistent with the theoretical calculation results. In this study, based on the first principle and MBE technology, the propagation characteristics of APD in on-axis GaAs/Si (001) materials are theoretically analyzed and experimentally verified. The results have a guiding significance for the experimental process exploration of growing high quality APD-free GaAs materials on on-axis Si (001) substrates by MBE technology and promote the research on high-performance on-axis silicon-based lasers by MBE technology.