Low work function of crystalline GeTe/Sb2Te3 superlattice-like films induced by Te dangling bonds

We utilized a GeTe/Sb2Te3 superlattice-like structure (SLL) to obtain a lower crystalline work function (WF) than that for GeTe. Electrostatic force microscopy measurements demonstrated the difference in crystalline WF. Due to the lower crystalline WF, the heterojunction diodes based on the SLL obtained a better crystalline electrical performance. We preformed numerical simulation to confirm that the higher number of Te dangling bonds caused by the multilayer interface and grain boundaries in the SLL is the main reason for the decrease in WF. X-ray photoelectron spectroscopy analysis indicated that more Te-O bonds formed in SLL than GeTe after atmospheric annealing. While it is easy for the Te dangling bonds to combine dipoles, more Te dangling bonds exist in SLLs.