Open‐circuit voltage decay: moving to a flexible method of characterisation

Abstract

Open-Circuit Voltage Decay is a method to characterize minority carrier effective lifetime (τ ef f). It is non-destructive, simple and low-cost. It has been mainly used in silicon p-n junctions. τ ef f is a very important parameter to optimize device design but also to supervise process steps. Actually, it is not the only parameter we can obtain by OCVD. Due to the intrinsic space charge region (SCR) capacitance of a p-n junction, doping level of the lowest-doped region (N l) and built-in potential (V bi) are extractable. Moreover, it is also possible to obtain the shunt resistance (R sh) value when it has a significant effect on the p-n junction behaviour. We first applied the well-established one-diode model in transient regime to simulate OCVD signal. In a second step, we used an optimization algorithm to fit the experimental curve of a silicon diode in order to extract τ ef f , N l , V bi and R sh. These values were compared to those obtained from C-V and I-V. Results are promising and demonstrates for the first time, the flexibility of the OCVD method. It opens up the perspective for development of add-on features of the method and for measuring short lifetime.

Sustainable Photocatalytic Biological Cofactor Regeneration Fueled by Selective Alcohol Oxidation over Polarized ZnIn2S4

“…Additionally, the open-circuit potential under illumination (Figure S14) and the corresponding decay curve (Figure S34) show that M 0.05 -ZIS and M 0.25 -ZIS possess a longer minority carrier effective lifetime than ZIS and M 1 -ZIS. 50 This verifies that the polarization effect (Figure 2f) and a stable crystal structure (Figure S4b) synergistically surmount the electron− hole Coulomb interaction and facilitate the transfer of photogenerated charge carriers. Steady-state photoluminescence (PL) responses reveal a characteristic emission peak centered at 520 nm, which is derived from the band-to-band transition of ZIS (Figure S35).…”

“…In contrast, the excessive Rh complex anchoring hinders carrier flow, consistent with the photocurrent results. Additionally, the open-circuit potential under illumination (Figure S14) and the corresponding decay curve (Figure S34) show that M 0.05 -ZIS and M 0.25 -ZIS possess a longer minority carrier effective lifetime than ZIS and M 1 -ZIS . This verifies that the polarization effect (Figure f) and a stable crystal structure (Figure S4b) synergistically surmount the electron–hole Coulomb interaction and facilitate the transfer of photogenerated charge carriers.…”

Selective Photocatalytic Reduction of 3‐Nitrophenol to 3‐Aminophenol by Anatase and Rutile TiO2 – What Stands Behind the Photoactivity?

“…This voltage drop is usually associated with the series resistances, where the second region, before the complete discharging of the electrode, is assigned to the recombination of minority charge carriers. [83] The k r values were determined for this second region (starting approximately 100-150 s after switching off the light) and are summarized in Table 2. A careful analysis of the obtained rate constants showed that the constants differ for the given materials, and a certain trend can be noticed.…”

On the design of measuring circuit for OCVD method

“…One of the possible explanations of this follows: The recombination current of charge carriers is not the dominant part of current flowing through the PN junction. The transient effect starts to be a discharging process of barrier capacity by the diffusion current or external admittance [5], [6].…”

“…The generator with semiconductor switch [7] on the Fig. 2c enables very good matching between the circuit and measurement's requirements [5], [11]. With using of small-power switching transistors we can generate pulses with the amplitude of several amperes and turnoff time several ns.…”