The Haynes-Shockley technique for the measurement of electron and hole drift mobility mu in semiconductors is here presented in a version suitable for an. The Haynes-Shockley Experiment. Minority carrier applet and tutorial, which describes generation by laser pulse, diffusion due to nonuniform concentration, drift. The ambipolar drift mobility of holes in n‐type HgCdTe with nominal composition of x= was determined by the Haynes–Shockley experiment.
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The point contacts are partially rectifying and therefore they are drawn as diodes in figure 1 By applying to the electrode E emitter a short negative pulse voltage with an amplitude large enough to forward bias the diode D Eelectrons will be injected into the crystal region underlying the emitter. Java Applets simulations of the Haynes-Shockley signal: Views Read Edit View history.
This electron pulse will drift, under the electric field action, with velocity v dand after some time t it will reach the region underlying the electrode C collector.
A simple and instructive version of the Haynes-Shockley experiment
When the excess electron pulse reaches the point contact C, the minority charge carrier density is locally increased, thus increasing the inverse current and producing a voltage drop across the resistance R. Bell System Technical Journal.
New version of the Haynes-Shockley experiment. Simulation 1 Simulation 2. The second pulse corresponds to the excess electon distribution passing under the collector contact: Example of collected pulses with different values of sweep voltage.
The first peak is simultaneous with the injection pulse: Two point contacts electrodes E and C are made by two metal needled separated by a distance d. LCD display measuring the flight distance, the sweep voltage and the laser intensity. Circuitry for testing the rectifying behavior of the point contact I-V curves. In our new setup hayhes excess carriers are optically injected using internal photoelectric effect avoiding the need of a reliable point-contact emitter.
The Haynes-Shockley experiment requires not included: However, as electrons and holes diffuse at different speeds, the material has a local electric charge, inducing an inhomogeneous electric field which can be calculated with Gauss’s law:.
The sample-holder with two gliders for optical fiber and point contact collector. Double pulser for the sweep voltage and for the laser-driving pulse, with a differential amplifier subtracting shockoey sweep voltage from the collector signal. In the following, we reduce the problem to one dimension.
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In the experiment, a piece of semiconductor gets a pulse of holes ehockley, for example, as induced by voltage or a short laser pulse. The block diagram of the original Haynes and Shockely experiment is shown in Fig. The semiconductor behaves as if there were only holes traveling in it.
From Wikipedia, the free encyclopedia. We consider the continuity equation:. Shockley to measure the drift mobility of electrons and holes in semiconductors is conceptually simple. We are interested in determining the mobility of the carriers, diffusion constant and shockleh time. Sample Holder with double glider for optical fiber motorized and for point contact.
Subscript 0s indicate equilibrium concentrations. Switchable polarity fpr P-doped and N-doped samples.
In semiconductor physicsthe Haynes—Shockley experiment was an experiment that demonstrated hsynes diffusion of minority carriers in a semiconductor could result in a current. The signal then is Gaussian curve shaped.
As an example, let us consider a P-doped semiconductor bar, of length lwith ohmic contacts soldered at both ends Inside the sample an electric field named sweep field E s is temporarily produced by a pulsed generator, sketched shockleu Figure 1 as a battery in series with a switch. The two initial equations write:.
P-doped Germanium sample with ohmic contacts.
A simple and instructive version of the Haynes-Shockley experiment – IOPscience
Retrieved from ” https: Experimwnt of the original H-S apparatus. Block diagram of the apparatus with optical injection. This can be interpreted as a Dirac delta function that is created immediately after the pulse. Optional N-doped Germanium sample with ohmic contacts. To see the effect, we consider a n-type semiconductor with the length d.