A new method of diode ideality factor extraction from dark I–V curve Nese Kavasoglu * , A. Sertap Kavasoglu, Sener Oktik Mugla University, Faculty of Arts and Sciences, Department of Physics, 48170-Kotekli, Mugla, Turkey article info Article history: Received 20 June 2008 Received in revised form 27 July 2008 Accepted 4 August 2008 Available online 12 August 2008 PACS: 73.40.Qv 73.40.Sx 73.30.+y 73.40.Ns 84.37.+q 61.80.x Keywords: Anomalous current–voltage characterization Curvature function p–i–n device Diode ideality factor BPW34 abstract Most of the techniques have been developed to extract diode ideality factor utilize the one-exponential diode model. However, for a correct description of two linear regions in the log I–V (current–voltage) graph of unipolar devices, one-exponential diode model is not sufficient. We have derived a new model which is named Beta (b) model for the calculation of diode ideality factor from dark current–voltage char- acteristic of the device (p–i–n device). Results obtained from our model are considerably in compliance with the experimental data. Ó 2008 Elsevier B.V. All rights reserved. 1. Introduction For semiconductor devices, it is important to obtain diode ide- ality factor because the ideality factor is an important parameter in the description of the device’s electrical behavior. Several meth- ods have been proposed for determining diode ideality factor [1– 11]. Traditionally, the methods used to extract the value of the ideality factor utilize the one-exponential diode model. However, for a correct-description of the two linear regions in the log I–V graph of unipolar devices, this single exponential model is not suf- ficient. For instance, dark I–V data of some unipolar device’s cannot be explained by single diode model. Sometimes, these types of de- vices exhibit double junction behavior [12–14]. Such devices may include series connected diodes in series with resistance [15]. At that point, one has to rewrite the I–V equation with respect to con- nection configuration of diodes or related passive components in the device’s equivalent circuit. Using appropriate I–V equations, one may attempt to curve fitting on measured I–V data with any suitable graphic editor program. But, if one looks more closely into these equations, one can see that there are a lot of unknown device parameters such as n 1 , n 2 , I 01 , I 02 and R s . Current methods for extracting parameters generally require curve fitting or some other iterative procedure. Nevertheless, if the number of unknown parameters increases, the iterative method goes to halt or runs more slowly. In other words, elapsed calculation time increases logarithmically. At that point, initial guess value for the investi- gated device parameter becomes crucial. If we enter closer initial guess values according to the most fitted device parameters, itera- tion time decreases sharply. This leads to a more quick solution to device parameters. Ordinarily, the electrical properties of unipolar devices have been analyzed using simple diode equations [14,16–18]. In this pa- per, attempts have been made to understand the device that have one or many potential barriers. The main objective of this paper is to propose a different theoretical model for the determination of diode ideality factor of the semiconductor device which contains series connected two diodes with series resistance. This model is named as ‘‘Beta model (b)”. b model directly concerns the mea- sured dark I–V data. Shunt resistance is considered to be about 10 20 X. Therefore, one may easily ignore shunt resistance in this study. 1567-1739/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.cap.2008.08.002 * Corresponding author. Tel.: +90 252 211 1674; fax: +90 252 223 86 56. E-mail address: knesese@gmail.com (N. Kavasoglu). Current Applied Physics 9 (2009) 833–838 Contents lists available at ScienceDirect Current Applied Physics journal homepage: www.elsevier.com/locate/cap