Thickness‐Controlled, Centimeter‐Scale 2D Cu 2 Te Films for 2.2 µm Photodetection

Two‐dimensional (2D) narrow‐bandgap semiconductors hold great promise in the field of mid‐infrared (MIR) optoelectronics due to their suitable bandgaps and unique physical properties. However, the controllable and scalable synthesis of 2D narrow‐bandgap semiconductors with precise thickness, stoichiometry, and lateral dimensions remains challenging. Here, the controllable synthesis of centimeter‐scale ultrathin 2D Cu 2 Te films via pulsed laser deposition (PLD) is reported, with the maximum lateral dimension of the fabricated films reaching 2 cm. The film thickness can be precisely controlled by the number of laser pulses while maintaining near‐stoichiometric composition, reaching a minimum thickness of two layers. Furthermore, photodetectors based on 2D Cu 2 Te exhibit a responsivity as high as 22 mA/W at a wavelength of 2200 nm, with a response time of approximately 15 ms, limited by the present modulation setup. This work establishes a scalable strategy for the synthesis of high‐quality 2D narrow‐bandgap material and highlights the potential of 2D Cu 2 Te for infrared optoelectronic applications.