Theory of the small-signal photovoltage at semiconductor surfaces

Study on dynamics of photoexcited charge injection and trapping in CdS quantum dots sensitized TiO2 nanowire array film electrodes

“…Although bulk defect energy levels of TiO 2 could have some contribution to their SPV or TPV, 9,20 however, just like our SPV results, no TPV signal was found. Perhaps because the TiO 2 nanowires have good crystallinity and low bulk defect, the SPV and TPV are too weak to detect.…”

Surface photovoltage phenomena: theory, experiment, and applications

“…In particular, the selective capture of electrons may induce a non-zero SPV response even if the bands are initially¯at. The latter case has been treated in detail by Buimistrov et al [69] as a`new form' of SPV, but has been shown to be only a special case soon thereafter [67].…”

“…where: [67]. The dependence of Q sc on Á n suf®ces to study the SPV in the case where Q ss (and hence Q sc ) does not change upon illumination (such a SPV is sometimes known as a`barrier SPV' [22] Ã s akTY n b ap b Y Á n back to its equilibrium value.…”

“…Thus, the charge neutrality condition implies that the sum of the space charge, the fast state charge, and the slow state charge is zero both in equilibrium and under illumination. A small-signal analysis of the SPV was performed by Brattain and Garrett [68] and later by Frankl and Ulmer [67] for the case of continuous and discrete surface state distributions, respectively. Within this analysis, it is possible to ®nd an explicit (albeit cumbersome) expression for dV s adÁ p , i.e., for the SPV obtained due to a small variation in the carrier injection factor at the edge of the SCR.…”

“…The reason is that under the assumptions of quasi-neutrality and FQL, the distribution of the majority carriers is completely speci®ed by that of the minority carriers. Such an approach has been used by Frankl and Ulmer [67] for obtaining explicit expressions of the small signal SPV. These expressions were further simpli®ed by Lile [74] for obtaining expressions which may be compared to experiment with relative ease.…”