X-Ray-Induced Bulk Photovoltaic Effect in Insulators

Abstract

When an insulator, sandwiched between metals of dissimilar work functions, is irradiated with x-radiation, a voltage related to the contact potential difference of the metals is observed. This phenomenon, known as the bulk photovoltaic effect, has been demonstrated in a variety of metal-insulator-metal combinations. Evidence that the voltage is not generated by junctions, barrier layers, or simillar other phenomena is presented.

X-ray Induced Electric Currents in Anodized Ta2O5: Towards a Large-Area Thin-Film Sensor

“…Our results confirm prior findings of bulk photovoltaic effect in metal–insulator-metal junctions where the contact potential difference between metals is the driving mechanism [ 19 , 26 ] and pave the way for the development of large area self-powered radiation sensors. The use of Ta-Ta 2 O 5 and other metal-metal-oxide electrodes as dosimeters was proposed by Feates and Knight in 1961 [ 20 ] but abandoned due to complexities of the measuring system and small signal compared to the background noise.…”

“…The use of Ta-Ta 2 O 5 and other metal-metal-oxide electrodes as dosimeters was proposed by Feates and Knight in 1961 [ 20 ] but abandoned due to complexities of the measuring system and small signal compared to the background noise. Several prior works focused on the radiation hardness of Ta capacitors rather than on their customization as radiation sensitive devices [ 15 , 16 , 17 , 19 , 21 ].…”

“…Transient prompt-dose effects in high energy density capacitors are also of interest in harsh radiation environments, such as prompt-gamma and X-ray irradiation in the order of 10 Gy in 20 ns radiation burst, where dielectric breakdown can be catastrophic [ 17 ]. Response of metal–insulator-metal (MIM) structures under UV [ 18 ] or X-ray [ 19 ] for radiation detection have been investigated in the past. Strong X-ray induced bulk photovoltaic effect has also been shown in thick anodized Ta 2 O 5 cells (0.1–3.5 µm oxides) with Ta and Au electrodes [ 19 ].…”

“…Response of metal–insulator-metal (MIM) structures under UV [ 18 ] or X-ray [ 19 ] for radiation detection have been investigated in the past. Strong X-ray induced bulk photovoltaic effect has also been shown in thick anodized Ta 2 O 5 cells (0.1–3.5 µm oxides) with Ta and Au electrodes [ 19 ]. The effect of radiation in Ta/Ta 2 O 5 film with electrolytic counter electrodes has shown linear relation between photocurrent and radiation intensity at low dose rate [ 20 ].…”

“…Our focus in this manuscript is the radiation response of Ta 2 O 5 capacitors in view of the development of large area Ta 2 O 5 anodization electrodes. In the past, only small samples of Ta 2 O 5 have been made and studied from a solid-state physics or electronic structure perspective [ 18 , 19 ]. Here, we are paving the way towards developing large area (≫1 cm 2 ) anodized Ta 2 O 5 sheets for radiation detection on large surfaces.…”