Zintl-phase Mg3Sb2 as an emerging infrared photodetector material on silicon

Infrared (IR) photodetectors integrated on Si are in critical demand for Internet of Things (IoT) and AI applications. We repositioned the Zintl-phase compound Mg3Sb2, widely known as a high-performance thermoelectric material, as a candidate for Si-integrated optoelectronics. We demonstrate the first epitaxial growth of Mg3Sb2 thin films on Si(001) substrates, revealing a unique c axis orientation with four threefold symmetric domains. A p–n heterojunction formed between p-type Mg3Sb2 and n-type Si exhibited clear rectification. Crucially, the device demonstrated a distinct photoresponse to short-wavelength infrared light (1450 and 1600 nm), where we obtained spectral sensitivity spectra and confirmed a linear dependence of the photocurrent on the incident power at infrared wavelengths. This work unveils Mg3Sb2's untapped optoelectronic properties, establishing Mg3Sb2/Si as a promising platform for IR photodetectors.