The use of wide-bandgap CuCl on silicon for ultra-violet photonics

gamma-CuC1 is a wide-bandgap (E-g = 3.395eV), direct bandgap, semiconductor material with a cubic zincblende lattice structure. Its lattice constant, a(CuCl) = 0.541 nm, means that the lattice mismatch to Si (a(Si) = 0.543 nm) is < 0.5%. gamma-CuCl on Si - the growth of a wide-bandgap, direct bandgap, optoelectronics material on silicon substrates is a novel material system, with compatibility to current Si based electronic/optoelectronics technologies. The authors report on early investigations consisting of the growth of polycrystalline, CuCl thin films on Si (100), Si (111), and quartz substrates by physical vapour deposition. X-ray diffraction (XRD) studies indicate that CuCl grows preferentially in the < 111 > direction. Photoluminescence (PL) and Cathodoluminescence (CL) reveal a strong room temperature Z(3) excitonic emission at similar to 387nm. A demonstration electroluminescent device (ELD) structure based on the deposition of CuCl on Si was developed. Preliminary electroluminescence measurements confirm UV light emission at wavelengths of similar to 380nm and similar to 387nm, due to excitonic behaviour. A further emission occurs in the bandgap region at similar to 360nm.