Self‐Powered Diamond Homojunction Photodetectors for Stable Ultraviolet Sensing Under High Temperatures

ABSTRACT Ultraviolet photodetectors (UVPDs) operating at high temperatures are critical for sensing in extreme environments such as aerospace, nuclear electronic systems, and flame warning. However, most existing UVPDs suffer from severe performance degradation, increased dark current, and the need for external bias as the operating temperature rises. Here, we report a self‐powered UVPD based on an unintentionally doped/boron‐doped diamond homojunction. Benefitting from the ultra‐wide bandgap and excellent thermal stability of the diamond, the device has achieved high optoelectrical properties under UV illumination with negligible performance degradation even at an operating temperature of up to 250°C. The device demonstrates a high rectification ratio of 1.8 × 10 9 , high specific detectivity of over 10 12 Jones, and fast response times of 3.45 ms/2.68 ms under 0 V bias. Moreover, the device shows excellent long‐term operating stability and achieves high‐contrast imaging applications with excellent temperature tolerance. These results highlight the promise of diamond homojunctions for reliable UV detection and imaging in harsh operating environments.