Effects of stoichiometry in undoped CdTe heteroepilayers on Si

Crystalline CdTe layers have been grown heteroepitaxially onto crystalline Si substrates to establish material parameters needed for advanced photovoltaic (PV) device development and related simulation. These studies suggest that additional availability of the intrinsic anion (i.e., Te) during molecular beam epitaxy deposition can improve structural and optoelectronic quality of the epilayer and the interface between Si substrate and the epilayer. This is seen most notably for thin CdTe epitaxial films (<; ~10 μm). Although these observations are foundationally important, they are also relevant to envisioned high-performance multijunction II-VI alloy PV devices-where thin layers will be required to achieve production costs aligned with market constraints.