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| courses:ast201:8 [2023/12/09 02:54] – asad | courses:ast201:8 [2023/12/09 22:39] (current) – [4.2 Photoabsorbers or photoconductors] asad | ||
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| - | ==== - Photoabsorbers | + | ==== - Photoabsorbers ==== |
| So far we have talked about the emancipation of electrons via lattice vibration and collision, but an a photon with a wavelength larger than the **curoff wavelength** can also emancipate an electron. The cutoff wavelength | So far we have talked about the emancipation of electrons via lattice vibration and collision, but an a photon with a wavelength larger than the **curoff wavelength** can also emancipate an electron. The cutoff wavelength | ||
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| For Si, the value of 1.1 $\mu$m. In astronomy we use semiconductors as photoabsorbers. A simple example is shown below. | For Si, the value of 1.1 $\mu$m. In astronomy we use semiconductors as photoabsorbers. A simple example is shown below. | ||
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| The photon stream promotes electrons to the conduction band leaving behind an equal number of holes in the valence band. This is a basic **detector** or **sensor** or **receiver** that converts energy into matter, photons into electrons. The greater the stream the higher the conductivity of the detector. If the voltage across the semiconductor is constant, the electrical current $i$ through the resistor $R_L$ would depend on the number of photons absorbed per second. | The photon stream promotes electrons to the conduction band leaving behind an equal number of holes in the valence band. This is a basic **detector** or **sensor** or **receiver** that converts energy into matter, photons into electrons. The greater the stream the higher the conductivity of the detector. If the voltage across the semiconductor is constant, the electrical current $i$ through the resistor $R_L$ would depend on the number of photons absorbed per second. | ||
courses/ast201/8.1702115663.txt.gz · Last modified: 2023/12/09 02:54 by asad