Impact of Mn doping on the ferroelectric photovoltaic effect in multidomain BiFeO₃ thin films under above-bandgap illumination

Abstract

While recent studies have revealed that chemical doping can enhance the photovoltaic (PV) response of ferroelectrics under light with photon energy (hν) lower than the bandgap energy (E g), its impact under above-bandgap illumination (hν > E g) is not fully understood. In this study, the PV response at hν > E g of Mn-doped BiFeO3 (BFO) thin films with a periodic stripe domain pattern is investigated. The short-circuit photocurrent density (J sc) and open-circuit voltage decrease with increasing Mn content. Analyses of the light-polarization angle dependence of J sc indicate that the PV response arises primarily from the non-centrosymmetric nature of crystal lattices in both the bulk and domain wall (DW) regions. In contrast, the contribution of local electric fields (E local) across DWs which dominates the PV response of undoped BFO films is significantly suppressed by doping. We consider that a screening effect by charged defects leads to a suppressed E local in the Mn-doped films.

Photovoltaic Effect of La and Mn Co-Doped BiFeO3 Heterostructure with Charge Transport Layers

“…This may be caused by the domination of the oxygen vacancies with an increase in the Mn amount, as shown in Figure 4d, which was reported to increase the recombination rate of photo-generated carriers [18]. Matsuo et al reported that the local electric field across the domain walls of BFO films could be suppressed by Mn doping due to a screening effect by charged defects [33].…”

Bulk photovoltaic effect in ferroelectrics

“…92) Owning to its attractive features, many researchers have investigated the ferroelectric, 93,94) magnetic, [95][96][97] piezoelectric, [98][99][100][101] capacitive, 102) and structural [103][104][105][106] properties of BFO and its solid solutions. The relatively small E g coexisting with the massive P s has motivated us to investigate their fundamental PV properties 4,16,22,56,107,108) and to develop PV devices. Ji et al 54) demonstrated the bulk PV effect by measuring the light polarization angle dependence of photocurrent flowing perpendicular to P s for (111)oriented BFO epitaxial thin films on STO substrates.…”