Open-circuit voltage decay

There are numerous techniques to measure the recombination lifetime. Some of the better known are photoconductive decay (13). diode reverse recovery (14). diode open circuit voltage decay (15). surface photovoltage (JL ) and forward-biased pn junction I-V characteristic (17. I will describe one particular photoconductive decay method, because it is a relatively new, non-contact method that requires no junctions. This makes it very suitable for a large number of measurements as for a process sequence characterization tool. 

A number of characterization methods for wafers are used today. One group of experiments aims at the purely electronic parameters like DLTS and Photoluminiscence. While DLTS and related measurements give information on the trap energies, methods like surface photovoltage (SPV) or open circuit voltage decay (OCVD) give information on effective diffusion length. 

What is impUed by unequal generation and recombination lifetimes The lifetime measurement techniques and the resulting lifetimes measured with them must be clearly understood to avoid confusion. For example, the recombination lifetime is measured by such methods as photoconductive decay, open-circuit voltage decay, diode reverse-recovery, surface photo voltage, electron-beam induced current and others. 

The open-circuit voltage decay (OCVD) lifetime characterization technique was one of the early lifetime measurement methods. [76] It is simple and is among the preferred lifetime characterization techniques because it is easy to implement It requires only a simple measurement circuit. The interpretation of the experimental data is fairly straightforward and a commercial instrument is available. 

Fig.6 A schematic open circuit voltage decay measurement circuit.

The open-circuit voltage decay V(t)-t curve of Fig.7(a) shows several... 

Fig.7 A schematic (a) and experimental (b) open circuit voltage decay curve.

Zaban A, Gieenshtein M, Bisquert J (2003) Determination of the electron lifetime in nanocrystalline dye solar cells by open-circuit voltage decay measurements. Chem Phys Chem 4(8) 859-864... 

Recently, Fletcher et al. has proposed for carbon-based supercapacitors, a general equivalent circuit through the comprehensive and reasonably dependable explanation through open circuit voltage decay, capacitance loss at high frequency, and voltammetric distortions at high scan rate [94]. Table 4 shows the few selected conducting polymer nanocomposite supercapacitor performances. 

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