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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Two point contacts electrodes E and C are made by two metal needled separated by a distance d. 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.
The semiconductor behaves as if there were only holes traveling in it. The second pulse corresponds to the excess electon distribution passing under the collector contact: The signal then is Gaussian curve shaped.
Shockley to measure fxperiment drift mobility of electrons and holes in semiconductors is conceptually simple. 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.
From Wikipedia, the free encyclopedia. Block diagram of the apparatus with optical injection. Circuitry for testing the rectifying behavior of the point contact I-V curves. Block diagram of the apparatus with optical injection The measurement of the time of flight t.
Holes then start experimebt travel towards the electrode where we detect them.
The measurement of the time of flight t. 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.
Java Experimwnt simulations of the Haynes-Shockley signal: However, as electrons and holes diffuse at different speeds, the shockleey has a local electric charge, inducing an inhomogeneous electric field which can be calculated with Gauss’s law:. The main difficulties are in the sample preparation, in the charge injection and in the signal detection. New version of the Haynes-Shockley experiment. Switchable polarity fpr P-doped and N-doped samples.
This can be interpreted as a Dirac delta function that is created immediately after the pulse. In our new setup the excess carriers are optically injected using internal photoelectric effect avoiding the need of a reliable point-contact emitter.
To see the effect, baynes consider a n-type semiconductor with the length d. The experiment proposed in by J. Setup of the original H-S apparatus. The injected electrons in fact, while drifting towards the collector, diffuse broadening their spatial distribution, so hayhes the width of the collected pulse increases with the time of flight t.
Simulation 1 Simulation 2. In semiconductor physicsthe Haynes—Shockley experiment was an experiment that demonstrated that diffusion of minority carriers in a semiconductor could result in a current. In the experiment, a piece of semiconductor gets a pulse of holesshockoey example, as induced by voltage or a short laser pulse.
Moreover the electrons recombine with holes so that their number decreases exponentially with time t as: LCD display measuring the haynex distance, the sweep voltage and the laser intensity. We consider the continuity equation:. This page was last edited on 21 Marchat P-doped Germanium sample with ohmic contacts.
The two initial equations jaynes. Double pulser for the sweep voltage and for the laser-driving pulse, with a differential amplifier subtracting the sweep voltage from the collector signal.
The sample-holder with two gliders for optical fiber and point contact collector.