Formation of pn junction pdf

Department of Electrical Engineering. Electrical engineers enlighten the world - moving information, people, things and energy to make tomorrow even better than today. •Electrostatics of pn junction in equilibrium -A space charge region surrounded by two quasi-neutral regions formed. •To first order, carrier concentrations in space charge region are much smaller than the doping level ⇒can use depletion approximation •From contact to contact, there is no potential buildup across the pn junction diode The P-N junction may be produced by and one of following methods. • Grown Junction diode • Alloy Junction diode • Diffusion Junction diode • Epitaxial growth Junction diode • Point Contact Junction diode INTRODUCTI ON. 5. GROWN JUNCTION DIODE • This type are formed during the crystal pulling process. the pn junction has rectifying behavior from a physics point of view. This is shown in Figure1. Forward biasing, refers to the application of a positive voltage at the p-side relative to the n-side. Reverse biasing is the opposite. Figure2indicates the structure and a corresponding circuit symbol of a pn junction (diode). P-n Junctions. A pn junction separates the electron and hole carriers in a solar cell to create a voltage and useful work. There are many other possible ways to extract carriers from a solar cell such as metal-insulator-semiconductor 1 or even carrier selective contacts 2, 3. However, a pn junction is the most common in use and the analysis A PN junction is a device formed by joining p-type ( doped with B, Al) with n-type (doped with P, As, Sb) semiconductors and separated by a thin junction is called PN Junction diode or junction diode. 5. Electronic Symbol …..the triangle shows indicated the direction of current P type N type Depletion layer forms an insulator between the 2 sides. Electrostatics: Junction Capacitance Capacitance per unit area [F/cm2] Figure 4.11 (Muller, Kamins 2003) (a) Dopant concentration in an arbitrarily doped junction, showing modulation of the carrier densities at the edges of the space-charge region by an applied voltage. (b) Electric-field distributions for two slightly different applied voltages. Equilibrium band diagrams appear below the semiconductor. The green horizontal line is the Fermi level. Initiate the pn junction formation by clicking the 'FormJunction' button or using mouse drag and watch the physical system approach a new (electro-thermal) equilibrium which is characterized by a constant Fermi level throughout the material. Zero Biased PN Junction Diode PN Junction N- region P- region Zero Bias Buil t-in Potential 0.3 -o.v The potential barrier that novv exists discourages the diffusion of any more majority carriers across the junction. Hovvever, the potential barrier helps minority carriers (few free electrons in the P-region and few holes in the N-region) to At the instant of PN junction formation, the free electrons near the junction in the n region begin to diffuse across the junction into the p region, where they combine with holes near the junction. Before the PN junction is formed, there are as many electrons as protons in the n-type material, making the material neutral in terms of charge. The same is true for the p-type material. When the PN junction is formed, the n region loses free electrons as they diffuse across the In a semiconductor, the P-N junction is created by the method of doping. The p-side or the positive side of the semiconductor has an excess of holes, and