Unusual Red Light Emission from Nonmetallic Cu2Te Microdisk for Laser and SERS Applications

Physical characteristics of Cu2Te are poorly investigated due to limited Te sources available and unclear atomic positions of crystal structure. Herein, hexagonal Cu2Te microdisks are successfully prepared via chemical vapor deposition procedure using GaTe as Te source. The epitaxial growth mechanism of the Cu2Te hexagonal structures with the orthorhombic phase is rationalized by proposed layer-over-layer growth model. The photoluminescence (PL) spectrum of Cu2Te microdisks shows a new red emission band in addition to usual infrared light emission due to Cu deficiency. Single Cu2Te microdisk operates as an optical microcavity supporting whispering gallery modes for red lasing around 627.5 nm. This Cu2Te microdisk microcavity exhibits a high quality factor of 1568 and a low lasing threshold of 125 kW cm(-2) at room temperature. Meanwhile, Cu2Te microdisks have been exhibited as an ideal platform for surface enhanced Raman scattering (SERS) eliminating drawbacks of noble metal substrates with detection limitation to nanomolar level and an enhancement factor of approximate to 1.95 x 10(5). Hexagonal Cu2Te microdisks turn out to be an efficient microcavity for red lasing and low-cost nonmetallic SERS substrates, opening potential applications in photonics and biological detection of aromatic molecules.