Schottky Contacts to ZnO-Nanocoated SnSe Powders by Atomic Layer Deposition

In this study, SnSe powders are nanocoated with ZnO grown by atomic layer deposition (ALD) with different ALD ZnO pulse cycles. Subsequently, the current transport mechanisms of Pt/ZnO-coated SnSe junctions are electrically investigated. A decrease in the current and an increase in the series resistance are observed at 300 K with increasing ZnO pulse cycles (i.e., increasing the thickness of the ZnO layer). The series resistance is similar at 450 K for all samples. The difference in the barrier height for each sample is insignificant, thus indicating that the ZnO coating marginally alters the barrier height at the Pt/SnSe junction. The inhomogeneous Schottky barrier can explain both the forward and reverse bias current conduction. The lowest ideality factor observed for the SnSe sample with ZnO 100 cycles is related to the lowest standard deviation (i.e., the lowest spatial fluctuation of the barrier height). Furthermore, the electrical conductivity is comparable to that of the sample without ZnO coating, thus suggesting that ZnO-coated SnSe by ALD can be considered to improve the thermoelectric device performance.