In a photodiode, light produce reverse current forward current electroluminescen

Question

In a photodiode, light produce reverse current forward current electroluminescence dark current Answers to odd numbered problems are at the end of the book. BASIC PROBLEM Use the practical diode model unless specified otherwise. Introduction to semiconductors List two semi conductive materials. How many valence electrons do semiconductors have? In a silicon crystal, how many covalent bonds does a single atom form? What happen when heat is added to silicon? Describe the process of doping and explain how it alters the atomic structure of silicon. What type of impurity is antimony? What type of impurity is boron? Explain what a hole is What is recombination The Diode How is the electric field across the pn junction created? Because of its barrier potential, can an diode be used as a voltage source? Explain. To forward - bias a diode, to which region must be positive terminal of a voltage be connected? Explain why a series resistor is necessary when a diode is forward - biased.

Explanation / Answer

2 semiconductors have 4 valence electrons 6 doping is adding impurities .... grp 13 or grp15 elements are added to semiconductors.. The synthesis of n-type semiconductors may involve the use of vapor-phase epitaxy. In vapor-phase epitaxy, a gas containing the negative dopant is passed over the substrate wafer. In the case of n-type GaAs doping, hydrogen sulfide is passed over the gallium arsenide, and sulfur is incorporated into the structure. This process is characterized by a constant concentration of sulfur on the surface. In the case of semiconductors in general, only a very thin layer of the wafer needs to be doped in order to obtain the desired electronic properties.The reaction conditions typically range from 600 to 800 °C for the n-doping with group VI elements, and the time is typically 6–12 hours depending on the temperature. 8 Holes are missing electrons. They behave as particles with the same properties as the electrons would have occupying the same states except that they carry a positive charge. This definition is illustrated further with the figure below which presents the simplified energy band diagram in the presence of an electric field. 12 n region is to be connected to positive voltage ...

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