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 second pulse corresponds to the excess electon distribution passing under the collector contact: The two initial equations write:. In semiconductor physicsthe Haynes—Shockley experiment was an experiment that demonstrated that diffusion of minority carriers in a semiconductor could result in a current. The signal then is Gaussian curve shaped. P-doped Germanium sample with ohmic contacts. To see the effect, we consider a n-type semiconductor with the length d.
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 block diagram of the original Haynes and Shockely experiment is shown in Fig. Example of rxperiment pulses with different values of sweep voltage.
Sample Holder with double glider for optical fiber motorized and for point contact. This can be interpreted as a Dirac delta function that is created immediately after the pulse.
Views Read Edit View history. Optional N-doped Germanium sample with ohmic contacts.
Simulation 1 Simulation 2. Circuitry for testing the rectifying behavior of the point contact I-V curves. From Wikipedia, the free encyclopedia. Shocjley diagram of the apparatus with optical injection The measurement of the time of flight t. The semiconductor behaves as if there were only holes traveling in it.
Haynes–Shockley experiment – Wikipedia
Expperiment System Technical Journal. Double pulser for the sweep voltage and for the laser-driving pulse, with a differential amplifier subtracting the sweep voltage from the collector signal. This page was last edited on 21 Marchat The first peak is simultaneous with the injection pulse: The main difficulties are in the sample preparation, in the charge injection and in the signal detection.
We consider the continuity equation:. Esperiment are interested in determining the mobility of the carriers, diffusion constant and relaxation time.
New version of the Shocley experiment.
A simple and instructive version of the Haynes-Shockley experiment
Haymes from ” https: 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. 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. Subscript 0s indicate equilibrium concentrations.
The injected electrons in fact, while drifting towards the collector, diffuse broadening their spatial distribution, so that the width of the collected pulse increases with the time of flight t. On the oscilloscope screen we may observe a first short negative pulse, with amplitude comparable to that of the injection pulse and, after some delay ta second ahockley pulse, wider and much smaller than the first one.
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 experiemnt, sketched in Figure 1 as a battery in series with a switch.