On Estimating Differential Conductance from Noisy I-V Measurements in Delineating Device Parameters

Abstract

Differential conductance is a key to characterizing a solid-state device. Estimation of differential conductance from current-voltage characteristic curve amounts to estimate the first order derivative from a discrete set of current-voltage measurements of the device under test. Conventional difference method in estimating derivative is inadequate when data contain noise. A robust method of estimating the first order derivative from a discrete set of evenly distributed current versus voltage measurements is designed where the method does not pose any constraints or limits on the data interval. The proposed method is formalized in the premise of the fundamental theorem of calculus and the inverse problem. The robustness of estimation is ensured using a regularization technique where the regularization operator is considered as a first order differential operator. A modified form of the L-curve technique is used to determine an optimal regularization parameter. The method is tested on synthetic and measured current-voltage characteristics of Schottky diode and MOSFET.