We have examined the band gap of a layered B${\mathrm{C}}_2$N compound semiconductor. The spectroscopic measurements of scanning tunneling microscopy showed the characteristics of a semiconductor with a band gap energy of 2 eV. The valence band edge measured by x-ray photoelectron spectroscopy was 0.95 eV below the Fermi level. Photoluminescence spectra showed a peak at 2.1 eV at room temperature and 4.2 K. These results were compared with the calculated band structures, and good agreement was obtained. It was concluded that the B${\mathrm{C}}_2$N is a semiconductor with a direct band gap which emits visible light.

• Received 21 March 1996

DOI:https://doi.org/10.1103/PhysRevLett.77.187