Notes on usage: Button click tends to respond very slowly.  It asks for your patience.  Click on the button just once and wait until the Label of the Button changes, for example, from Stop to Start.  Then the Checkboxes become enabled and you may set different conditions.

This applet visualizes the following processes of excess minority carriers in a semiconductor:

• - generation of excess carriers, by a laser beam,
• - diffusion, due to the concentration gradient,
• - drift, by the applied bias (or electric filed), and
• - the recombination loss.

If you click on the Stop button, the process stops. The Start button initiates a new process. The Pause/Resume button temporarily halts the process so that the data can be recorded or a momentary snap shot of the process can be examined.

The three checkboxes, width vs. t, displcmnt vs. t, N vs. t, display the data for the width of concentration profile, the displacement of the peak from its initial position, and the total number of excess minority carriers, respectively, as a function of time for the first 100 microseconds.

Quizz:

1. Which minority-carrier process is responsible for the width vs. t data ?
• Diffusion
• Drift
• Recombination
• Generation
2. Which minority-carrier process is responsible for the displacement vs. t data ?
• Diffusion
• Drift
• Recombination
• Generation
3. Which minority-carrier process is responsible for the N vs. t data ?
• Diffusion
• Drift
• Recombination
• Generation

Since the minority carrier lifetimes are long in Ge, as compared to Si and GaAs, the example is given for Ge.

You can change the conduction type, bias value, length of the sample, temperature, lifetime, and mobility (of minority carrier) using the bottom panel and examine their effects on the excess minority carrier processes.

By C.R.Wie.
(c) Copyright C.R.Wie, 1998-1999
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