Comparison of electrical characteristics of thin tellurium layers obtained from chemical solution and by thermal evaporation in vacuum

Abstract

Two-dimensional or other thin materials have high potential for use in next-generation electronic and optoelectronic devices. Recently, tellurium has gained much interest due to its broad applicability prospects. In this work, the physical properties of thin tellurium layers fabricated using two relatively simple and inexpensive technologies based on the deposition from a chemical solution and by thermal evaporation were compared. The morphology of the grown surfaces was analyzed using atomic force microscopy. The chemically deposited tellurium surface consists of nanometer-sized flakes, while polycrystalline layers are formed in the case of deposition by thermal evaporation. Additionally, the characteristics of the fabricated samples varied depending on their thickness, as observed in both Raman spectroscopy and THz spectroscopy measurements. Furthermore, the non-contact optical pump THz probe technique revealed that the layers had different carrier lifetimes and mobilities. The carrier lifetime of samples deposited by thermal evaporation is short, less than 40 ps, with mobility up to a few hundred cm2/V s. In contrast, chemically deposited samples have a longer carrier lifetime, ranging more than 500 ps, and superior mobility up to 1000 cm2/V s.