The Lateral Photovoltaic Effect in the Fe/SiO₂/ Si Structure with Different Silicon Conductivity Type

Abstract

We report on the results of the study of the lateral photovoltaic effect in the Fe/SiO2/Si structures with n-and p-type silicon. It is found that in both cases the photovoltage signal varies linearly when the light spot moves between the electrodes. It is established that the sensitivity of lateral photovoltaic effect in Fe/SiO2/n-Si and Fe/SiO2/р-Si structures is 32.3 and 14.7 mV/mm, respectively. When the silicon conductivity type changes, there is an inversion of photovoltage polarity as a result of the opposite direction of the built-in electrical field at the SiO2/Si interface. It was found that the response time in the Fe/SiO2/n-Si structure is 4.2 times faster than in the Fe/SiO2/p-Si structure due to the presence of an inversion layer in this structure.

Features of the Band Structure and the Mechanism of Lateral Photoconductivity in Hybrid Structures T/SiO-=SUB=-2-=/SUB=-/Si(T=Fe,Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=-, TiO-=SUB=-2-=/SUB=-)

“…It should be noted that the extreme dependence of LPE sensitivity on the thickness of the upper layer has been observed earlier in works [9][10][11][12][13][14][15][16][17][18]. Generally, the nature of the change in thickness dependence of LPE sensitivity is explained from two perspectives.…”

“…These surface states pin the Fermi level, and lower the height of the built-in barrier [26,27]. Earlier we have shown [16,17] that ignoring the surface states leads to a mismatch between the experimental LPE results and the parameters of the idealized energy band diagrams. By comparing Fig.…”

“…It should be noted that most works on LPE in MOS structures propose a model of current transfer, according to which, the photo-generated carriers are separated by an built-in field and are thrown into the upper metallic layer [11,13], and the LPE theory developed earlier for p−n-transitions [1,2] is used to analyze the LPE characteristics. On the other hand, the authors of some works [10,[14][15][16][17][18] believe that the inversion layer at the SiO 2 /Si interface contributes to the lateral photovoltage, assuming the photocurrent flows through the inversion layer, and the role of the metal film in this case is reduced to forming p−n-transition at the interface. Thus, the question about the mechanism of lateral photoconductivity remains open.…”

“…Magnetite (Fe 3 O 4 ) and titanium dioxide (TiO 2 ) were chosen due to their high resistivity and oxidation resistance. A detailed study of LPE in Fe/SiO 2 /Si and Fe 3 O 4 /SiO 2 /Si structures formed on silicon substrates of both conductivity types has been done by us earlier [16,17]. It was found [17] that in the Fe/SiO 2 /Si structure, LPE is observed at both types of substrate conductivity, but with different sensitivity.…”

“…A detailed study of LPE in Fe/SiO 2 /Si and Fe 3 O 4 /SiO 2 /Si structures formed on silicon substrates of both conductivity types has been done by us earlier [16,17]. It was found [17] that in the Fe/SiO 2 /Si structure, LPE is observed at both types of substrate conductivity, but with different sensitivity. Whereas in the Fe 3 O 4 /SiO 2 /Si structure, as shown in [16], linear LPV dependence was observed only on the n-type substrate, while on the p-type substrate, photo-voltage was observed only in the near-contact regions.…”