Atomic Layer Deposition Route to Scalable, Electronic-Grade van der Waals Te Thin Films

Scalable production and integration techniques for vander Waals(vdW) layered materials are vital for their implementation in next-generationnanoelectronics. Among available approaches, perhaps the most well-receivedis atomic layer deposition (ALD) due to its self-limiting layer-by-layergrowth mode. However, ALD-grown vdW materials generally require highprocessing temperatures and/or additional postdeposition annealingsteps for crystallization. Also, the collection of ALD-produciblevdW materials is rather limited by the lack of a material-specifictailored process design. Here, we report the annealing-free wafer-scalegrowth of monoelemental vdW tellurium (Te) thin films using a rationallydesigned ALD process at temperatures as low as 50 & DEG;C. They exhibitexceptional homogeneity/crystallinity, precise layer controllability,and 100% step coverage, all of which are enabled by introducing adual-function co-reactant and adopting a so-called repeating dosingtechnique. Electronically, vdW-coupled and mixed-dimensional verticalp-n heterojunctions with MoS2 and n-Si, respectively, aredemonstrated with well-defined current rectification as well as spatialuniformity. Additionally, we showcase an ALD-Te-based threshold switchingselector with fast switching time (& SIM;40 ns), selectivity (& SIM;10(4)), and low V (th) (& SIM;1.3 V).This synthetic strategy allows the low-thermal-budget production ofvdW semiconducting materials in a scalable fashion, thereby providinga promising approach for monolithic integration into arbitrary 3Ddevice architectures.

Automated summary

In this paper, a low-temperature ALD process is reported to achieve annealing-free growth of monoelemental vdW tellurium thin films with exceptional homogeneity, crystallinity, and layer control. The introduction of a dual-function co-reactant and the adoption of a repeating dosing technique enable the successful demonstration of electronically vdW-coupled and mixed-dimensional vertical p-n heterojunctions. The ALD-Te-based threshold switching selector with fast switching time, high selectivity, and low threshold voltage showcases the potential of this synthetic strategy for scalable production of vdW semiconducting materials for monolithic integration into arbitrary 3D device architectures.