## 1 Introduction  
Nowadays, two-dimensional (2D) materials are popular in materials science research as a rising star after [PERSON] put forward the concept of graphene [1]. People have put great amount of efforts to make large area graphene for practical applications. There have been some successes in growing large area and high-quality graphene films by ultrafast growth techniques [2, 3]. However, because of limitations, such as the zero band gap, the broad application of graphene is still challenging. Transition-metal dichalcogenides [4], such as MoS\({}_{2}\), WS\({}_{2}\), MoSe\({}_{2}\), and WTe\({}_{2}\), have drawn people's attention for their non-zero band gaps, but the electron mobility is not efficiently high. Novel 2D materials of group V elements, such as black phosphorus [5, 6, 7], arsenene [8, 9], antimonene [8, 9], and bismuthene [10], are gradually theoretically proposed and experimentally realized. Although black phosphorus has a tuneable band gap from 0.3 eV to 2.0 eV and a high carrier mobility, it is not stable in the air.  
[PERSON] [8] et al. first predicted antimonene, as the monolayer format of antimony. It is a stable semiconductor with a tuneable band gap and high electrical mobility. Later more antimonene characteristics were predicted [11], such as the effect of interfacial distance [12], heterostructures [13], doping [14], thermal conductivity [15], optical properties [16; 17], and so on. It has a wide indirect band gap and its band edge can be tuned by applying strain [8]. It can endure higher strain due to its van der Waals feature [18; 19; 20]. At the same time, antimonene growth has been attempted in a number of works [21; 22; 23] through molecular beam epitaxy (MBE) or other growth methods. Until now, beside \(\beta\)-antimonene, scientists have successfully grown honeycomb antimonene [24] and \(\alpha\)-antimonene [25] structures. As for the substrate choice, GaAs(111) [26], Ge(111) [27], c-plane sapphire [28], Ag(111), and h-BN [24; 29] have either been proposed or tried. However, experimental evidence is still insufficient in this area. For example, although antimonene has been made [30], the size is only in the nanometer level. Commonly available characterization methods, such as X-ray diffraction (XRD) and Raman spectra, cannot provide strong enough evidences. A distinctive Raman shift of antimonene is yet to be confirmed [25; 28; 31].  
Based on this background, we decided to grow antimonene on c-plane sapphire substrates. There are several reasons that we choose c-plane sapphire. Firstly, it is a stable, high-melting-point insulator, which does not contribute to the electrical characterization of the antimonene. Besides, it has a hexagonal structure that is similar to that of antimonene, and it can offer a 13.4% biaxial strain, according to theoretical calculation [8]. More importantly, van der Waals epitaxy has more opportunities to be achieved because of the absence of dangling bonds on the surface. During the growth study, we found that growth temperature played an important role in modulating the surface energy, therefore, to affect several key processes, such as adsorption, cracking of the source molecules, and the antimonene nucleation. Moreover, we have used high resolution XRD not only to obtain the antimonene quality, but also to reveal the competition between 2D antimonene and three-dimensional (3D) antimony growth processes. In addition, choices of Sb\({}_{2}\) or Sb\({}_{4}\) molecules could affect the electrical properties of the grown samples. These results not only provide a potential method to grow antimonene on more commonly available substrates, but also critical parameters that can promote the 2D growths.