CdTe is a well known and widely used binary compound for optoelectronic
applications. In this study, we propose the thinnest, free standing monolayer
of CdTe which holds the tetragonal-PbO (alpha-PbO) symmetry. The structural,
electronic, vibrational and strain dependent properties are investigated by
means of first principles calculations based on density functional theory. Our
results demonstrate that the monolayer alpha-CdTe is a dynamically stable and
mechanically flexible material. It is found that the thinnest monolayer crystal
of CdTe is a semiconductor with a direct band gap of 1.95 eV, which corresponds
to red light in the visible spectrum. Moreover, it is found that the band gap
can be tunable under biaxial strain. With its strain-controllable direct band
gap within the visible spectrum, stable alpha-phase of monolayer CdTe is a
suitable candidate for optoelectronic device applications
