Surface-Reaction-Controlled Initial Growth of Ir-Rich IrTe x Thin Films via ABC-Type Atomic Layer Deposition

Abstract Iridium telluride thin films are promising materials for electronic and optoelectronic applications, but their low-temperature deposition remains challenging. Although atomic layer deposition (ALD) is well-suited for low-temperature thin-film growth, ALD of platinum-group metal (PGM) tellurides is still largely unexplored because of limited precursor/reactant combinations and the inherent nucleation delay of iridium ALD. Here we report the first ALD process for Ir-rich IrTex thin films using tricarbonyl(η-1,2,3-tri-tert-butylcyclopropenyl)iridium (TICP) and bis(trimethylsilyl) telluride (BTMS-Te)/methanol (MeOH) as the iridium precursor and tellurium reactant, respectively. Furthermore, incorporating an intermediate O2 step established a surface-reaction-controlled ABC-type process. Compared with the AB-type process, this strategy increased the nucleation density by ∼41% and the average nucleus size by ∼2.6-fold, enabling the formation of continuous ultrathin IrTex films. Optimized IrTex/n-Si photodetectors exhibited self-powered broadband photoresponse in the 400–1550 nm range. These findings demonstrate a practical strategy for overcoming nucleation-limited growth during the ALD of PGM tellurides.