In the lab, you wish to measure the conductivity of a thin film semiconducting sample. One method you use is what is kno

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In The Lab You Wish To Measure The Conductivity Of A Thin Film Semiconducting Sample One Method You Use Is What Is Kno 1 (126.29 KiB) Viewed 26 times

In the lab, you wish to measure the conductivity of a thin film semiconducting sample. One method you use is what is known as a four-point probe, which is used to measure the resistivity. The basic setup of a four-point probe is shown below. During measurement, the four equally spaced probes are lowered to be in contact with the sample. A current is supplied through the outer probes and a voltage is measured across the inner probes. X2 Wafer Figure 1. Schematic of 4 point probe configuration (Top View, blue rings of current) a) For a thin film sample, you have derived an expression for the resistance between points x, TV dur and x, to be R = In 27. Given that the differential resistance is dRP PĀ, derive an expression for the conductivity o. The cross-sectional area A = 2axt for a sample of thickness t through which current flows is shown above on the right. b) You measure two films with the following doping characteristics. Calculate the electron and hole mobilities. Doping (12.m) n n (m) 8.7 x 1023 P (m) 8.7 x 1023 Intrinsic 8.9 x 10 Extrinsic (p-type) 2.3 x 105 7.6 x 1022 1.0 x 1025