The performance of ultraviolet solar-blind detection of p-Si/n-Ga₂O₃ heterojunctions with/without hole-blocking layer

The wide band gap semiconductor Ga₂O₃ has become an excellent UV detection material due to its suitable band gap, high crystalline quality and thermal stability. In this paper, the microstructure of Ga₂O₃ with different thicknesses is characterized and the solar-blind detection performance of Ga₂O₃/p-Si heterojunctions are further investigated. XRD and UV–VIS demonstrate that Ga₂O₃ sputtered for 20 min is amorphous with a band gap of 4.98 eV, as the sputtering time increases, Ga₂O₃ grows along the (002) crystal plane and the band gap increases. XPS reveals that the lattice oxygen content in the Ga₂O₃ increases with the sputtering time, however, the Ga³⁺ content reaches a peak in Ga₂O₃ sputtered for 1.5 h. And the increasing of the binding energy between Ga-O in Ga₂O₃/p-Si heterojunctions accelerates response speed. Electrical experiments show that the heterojunction consisting of sputtered 1.5 h Ga₂O₃ and p-Si reaches a higher PDCR, with a value of 6684 at 5.7 V. Meanwhile, the rise and decay time of the heterojunction are 0.13 s and 0.14 s at 0 V, and the decay time gradually increases from 0.1 to 0.7 s with increasing the applied voltage. However, insertion of 20 nm Si-doped Ga₂O₃ as a hole-blocking layer at the interface of p-Si and Ga₂O₃ remarkably declines the decay time under various applied biases and causes no obvious damage to the photo current of the heterojunction.