Asymmetric polarization modulation of self-powered deep-ultraviolet photodetector based on an epitaxial <b> <i>β</i> </b> -Ga2O3/PZT heterojunction

Abstract

Self-powered deep-ultraviolet photodetectors (DUV PDs) based on heterojunctions attract broad interest for their low-power operation and high portability. However, their performance remains limited by inefficient separation and transport of photogenerated carriers under the built-in electric field (Eb). Here, a ferroelectric-enhanced self-powered DUV PD based on an epitaxial β-Ga2O3/PZT heterojunction is developed, enabling nonvolatile polarization modulation of the electric field in the junction region. Zero-bias photoresponse measurements indicate that, in the upward-polarized state, constructive superposition of the forward depolarization electric field (Edp) and the Eb significantly increases the responsivity and detectivity to 476 mA/W and 2.37 × 1012 Jones, corresponding to enhancements of 283% and 98%, respectively. Notably, in the downward-polarized state, the reverse Edp opposes the Eb and is expected to suppress device performance strongly, yet the responsivity and detectivity exhibit only modest decreases of 48% and 27%, respectively. This asymmetric polarization modulation might be associated with an interfacial Pb-vacancy-enriched sheet revealed by the transmission electron microscope and the mobile oxygen vacancies. In the downward-polarized state, oxygen vacancies accumulate near the heterointerface and electrostatically couple to the Pb-vacancy-enriched sheet, which generates a compensating electric field aligned with the Eb and thereby partially counteracts the reverse Edp. These results provide a new route for developing, optimizing, and interpreting high-performance Ga2O3-based self-powered DUV PDs.