The MIT Microelectronics WebLab is a remote microelectronics device characterization laboratory. It allows users to measure the current-voltage characteristics of diodes and other microelectronics devices remotely, using a Java-enabled web browser. To run the Microelectronics WebLab, you must have a Java 1.4.2 plug-in installed, available from Sun's web site. You must also enable pop-ups.
Basic Diode Experiment
First, you will need to create an account at the WebLab web site. Account group permissions are manually approved; as a result, there may be up to a 24 hour delay between when you create the account, and when you can run the WebLab experiments. Once your account has been enabled, log in, and select the group appropriate for your class. Select the graphical client, and from there, select Launch Client. You may be asked whether you authorize the downloading of the WebLab client software to your computer; approve this. After a short download and startup time, the client should appear in a new window:
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We will now walk you through the simplest WebLab experiment – - testing the properties of a PN diode. When the client is launched, it automatically makes the diode experiment available to you. The diode symbol has a triangle pointing into a vertical line. The diode is connected to an instrument that is going to perform the actual measurements – - an Agilent 4155B Semiconductor Parameter Analyzer. The boxes labeled SMU1 and SMU2 correspond to the signal measurement ports of this 4155B. Characterizing the electrical behavior of the PN diode requires that these two SMU's be programmed appropriately.
Click on the box labeled SMU1. This will open a dialog box that allows you to configure SMU1. Since this is the anode, label the voltage Va and the current Ia. Check the download checkbox for both (WebLab will only allow you to plot the voltages and currents that you download). Set SMU1 to voltage mode, with the function set as Variable 1. Configure the voltage to sweep the voltage from -1.5V through 1.5V in 10mV increments. Do not adjust the compliance setting – - this sets the maximum current that the 4155B will allow on any terminals, so as not to damage the device (this setting will be correctly preconfigured, and will depend on the type of diode currently in the system):
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Congratulations! You have successfully completed your first WebLab measurement.
Transistor Experiment
This tutorial walks you through a slightly more complicated experiment – - analyzing a transistor.
First, if you have not already done so, you will need to create an account at the WebLab web site. Account group permissions are manually approved, and as a result, there may be up to a 24 hour delay between when you create the account, and when you can run the WebLab experiments. Once your account has been enabled, log in, and select the group appropriate for your class. Select the graphical client, and from there, select Launch Client. You may be asked whether you authorize the downloading of the WebLab client software to your computer; approve this. After a short download and startup time, the client should appear in a new window:
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