Co-Deposition of Bismuth and Nitrogen on Different Substrates Using Molecular Beam Epitaxy

In recent years, bismuth and its compounds such as Bi₂Te₃, Bi₂Se₃, and BiSb have attracted considerable attention due to many exotic quantum phenomena.^1-3 However, the nitride film of bismuth has remained unexplored. We deposited Bi and N on MgO(001) and Al₂O₃(0001) substrates. The grown samples were characterized by <i>in–situ</i> reflection high energy electron diffraction, Auger electron spectroscopy, and scanning tunneling microscopy, and studied <i>ex-situ</i> using X-ray diffraction and Rutherford backscattering. Many samples were grown on both types of substrates at different temperatures ranging from 100 to 450 degrees C, and we figured out the correct temperature for the co-deposition. Moreover, AES and RBS were used to compute the stoichiometry of the films. We observed that the lower growth temperatures and nitrogen-rich conditions are the most favorable for the co-deposition. Although the noticeable peak of nitrogen was observed in the Auger spectra, the RBS showed a comparatively low amount of nitrogen in the film. It could be due to the diffusion of the bismuth into the substrate, forming a new compound with the substrate material. And yet, we also found that the sample changed from a white color to a black color if the deposited Bi:N flux ratio was increased from 1:1.75 (or less) up to 1.4:1. This indicates that the nitrogen is playing a role in the film growth. This research has been supported by the US DOE, BES, DMSE under Award No. DE-FG02-06ER46317.<br/><br/>¹K. F. Zhang, Fang Yang, Y. R. Song, Canhua Liu, Dong Qian, C. L. Gao, and Jin-Feng Jia,Appl. Phys. Lett. <b>107</b>, 121601 (2015)<br/><br/>²Dima Sadek, Daya S. Dhungana, Roland Coratger, Corentin Durand, Arnaud Proietti, Quentin Gravelier,<br/>Benjamin Reig, Emmanuelle Daran, Pier Francesco Fazzini, Fuccio Cristiano, Alexandre Arnoult,<br/>and Sébastien R. Plissard,ACS Appl. Mater. Interfaces <b>13</b>, 36492−36498 (2021)<br/><br/>³Mu Chen, Jun-Ping Peng, Hui-Min Zhang, Li-Li Wang, Ke He, Xu-Cun Ma, and Qi-Kun Xue,Appl. Phys. Lett. <b>101</b>, 081603 (2012)