In this paper, a technique based on genetic algorithms is proposed for improving the accuracy of solar cell parameters extracted using conventional techniques. The approach is based on formulating the parameter extraction as a search and optimization problem. Current–voltage data used were generated by simulating a two-diode solar cell model of specified parameters. The genetic algorithm search range that simulates the error in the extracted parameters was varied from ± 5t o±100% of the specified parameter values. Results obtained show that for a simulated error of ±5% in the solar cell model values, the deviation of the extracted parameters varied from 0.1 to 1% of the specified values. Even with a simulated error of as high as ±100%, the resulting deviation only varied from 2 to 36%. The performance of this technique is also shown to surpass the quasi-Newton method, a calculus-based search and optimization algorithm.

https://iopscience.iop.org/article/10.1088/0957-0233/12/11/322/pdf

Solar cell parameter extraction using genetic algorithms

We describe a parameter extraction technique for the simultaneous determination of physical parameters in nonideal Schottky barrier, p-n and p-i-n diodes. These include the ideality factor, saturation current, barrier height, and linear or nonlinear series, and parallel leakage resistances. The suggested technique which deals with the extraction of bias independent parameters makes use of the forward biased current–voltage (I–V) characteristics and the voltage-dependent differential slope curve α(V)=[d(ln I)]/[d(ln V)]. The method allows (a) establishment of the current flow mechanisms at low and high bias levels, (b) extensive of the permissible ranges of determined parameters beyond what is possible in other published methods, and (c) to automation and computerization of the measurement processes. The method is verified experimentally using metal–semiconductor structures based on Si, InGaP, and HgCdTe as well as an InGaAs/InGaAsP multiple quantum well laser diode exemplifying a p-n junction.

On the extraction of linear and nonlinear physical parameters in nonideal diodes

We compare different I–V methods to extract junction parameters with a special emphasis on low series resistance determination. We have established the first method, the second method is based on the derivative (we use three formulae derived from dV/dI), the third method based on the integral (∫IdV) and the final one which is the method of Lee et al. (Lee TC, Fung S, Beling CD, Au HL. J Appl Phys 1992;72:4739). The comparison is performed using a simulated case with random noise. The above methods give good results, especially the derivative although it is dependent on voltage step. The latter is not the case with our method. In addition this latter method is very simple to use. We also deal with a solar cell with two exponential conduction processes and a shunt resistance. The fitting of the curve gives good results and our method permits to determine the boundary between the two processes and to obtain good initial values for a numerical fit of the whole curve.

I–V methods to extract junction parameters with special emphasis on low series resistance

We have developed a new method to analyze the forward ac behavior of a semiconductor diode that uses a series mode. This method can accurately measure the dependence of series resistance, junction capacitance, junction voltage, ideality factor, and interfacial layer on forward bias voltages. Giant negative capacitance (NC) of the junction and the interfacial layer with nonlinear resistance and capacitance are confirmed in GaN Schottky diodes.

Accurate electrical characterization of forward AC behavior of real semiconductor diode: giant negative capacitance and nonlinear interfacial layer

We describe a technique to extract device parameters of a Schottky barrier diode whose barrier height is bias dependent and which contains a linear series resistance. The extracted parameters include the saturation current (zero bias barrier height), the voltage dependence of the barrier height and of the ideality factor as well as series resistance. The technique makes use of forward biased current‐voltageOI‐VU characteristic and voltage-dependent diAerential slope curve aa dl nI OU = dl nV OU . The method is verified using simulated and experimental I‐V curves of an Al‐pSi structure. The proposed procedure is not limited to Schottky barrier diodes but may be applied to other diode types based on P‐N junction. ” 2001 Elsevier Science Ltd. All rights reserved.

Extraction of Schottky diode parameters with a bias dependent barrier height

We propose two novel methods of determining nonideal Schottky and p‐n junction diodes parameters from I–V plots. The series resistance Rs, saturation current Is, as well as the bias‐dependent ideality factor n(V), can be obtained from two successive I–V measurements—one solely of the diode and the other with an external resistance added in series with the measured diode. Our analysis confirms that the methods produce accurate and reliable results even when the conventional techniques fail, such as when we have strongly varying function n(V) in the presence of series resistance and an experimental noise.

M. Lyakas

Papers

Analysis of nonideal Schottky and p‐n junction diodes—Extraction of parameters from I–V plots