To understand how a pn-junction diode works, begin by imagining two separate bits of semiconductor, one n-type, the other p-type. As a result, the free electrons and holes near the junction tend to eat each other, producing a region depleted of any moving charges. This creates what is called the depletion zone.
Working Principle: A light-emitting diode is a two-lead semiconductor light source. It is a p–n junction diode that emits light when activated. When a suitable voltage is applied to the leads, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons.
The function of a regulator is to provide a constant output voltage to a load connected in parallel with it in spite of the ripples in the supply voltage or the variation in the load current and the zener diode will continue to regulate the voltage until the diodes current falls below the minimum IZ(min) value in the
P-n junctions are formed by joining n-type and p-type semiconductor materials, as shown below. Since the n-type region has a high electron concentration and the p-type a high hole concentration, electrons diffuse from the n-type side to the p-type side.
It occurs in a reverse biased p-n diode when the electric field enables tunneling of electrons from the valence to the conduction band of a semiconductor, leading to a large number of free minority carriers which suddenly increase the reverse current. The I-V curve for a diode showing avalanche and Zener breakdown.
Depletion Region. When a p-n junction is formed, some of the free electrons in the n-region diffuse across the junction and combine with holes to form negative ions. In so doing they leave behind positive ions at the donor impurity sites.
The breakdown voltage of an insulator is the minimum voltage that causes a portion of an insulator to become electrically conductive. For diodes, the breakdown voltage is the minimum reverse voltage that makes the diode conduct appreciably in reverse. Some devices (such as TRIACs) also have a forward breakdown voltage.
A diode is formed by joining two equivalently doped P-Type and N-Type semiconductor. When they are joined an interesting phenomenon takes place. The P-Type semiconductor has excess holes and is of positive charge. The N-Type semiconductor has excess electrons.
Knee voltage is also known as “cut-in-voltage". The minimum amount of voltage required for conducting the diode is known as “knee voltage” or “cut-in-voltage". And also said as The forward voltage at which the current through PN junction starts increasing rapidly is known as knee voltage.
Depletion region or depletion layer is a region in a P-N junction diode where no mobile charge carriers are present. Depletion layer acts like a barrier that opposes the flow of electrons from n-side and holes from p-side.
Diodes. A diode is a discrete component that allows current to flow in one direction only. It is a polarised component with two leads, called the cathode and the anode. The cathode is normally marked with a silver or coloured band or the symbol '-'.
The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction), while blocking it in the opposite direction (the reverse direction). As such, the diode can be viewed as an electronic version of a check valve.
The first thing we want to do is look at diode characteristics.
- Diode Characteristics. A diode is simply a PN junction, but its applications are extensive in electronic circuits.
- Diode Elements.
- Ideal Diodes.
- Practical Diodes.
- Practical Diode Forward Bias.
- Reverse Bias.
- Exceed Breakdown Voltage.
- Current Versus Voltage.
N-type silicon (red) has extra electrons (black). Battery connected across the p-n junction makes the diode forward biased, pushing electrons from the n-type to the p-type and pushing holes in the opposite direction. Electrons and holes cross the junction and combine.
In semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region, space charge region or space charge layer, is an insulating region within a conductive, doped semiconductor material where the mobile charge carriers have been diffused away, or have been forced away by an
As more electrons and holes flow in the depletion region the number of positive and negative ions is reduced, causing the depletion region to narrow. The energy loss in overcoming the barrier potential results in a voltage drop across the PN junction equal to the barrier potential. ( 0.7V for Si, 0.3V for Ge.)
The first semiconductor diodes, called cat's whisker diodes, developed around 1906, were made of mineral crystals such as galena. Today, most diodes are made of silicon, but other semiconductors such as selenium or germanium are sometimes used.
Formation of a P-n junction. P-n junctions are formed by joining n-type and p-type semiconductor materials, as shown below. Since the n-type region has a high electron concentration and the p-type a high hole concentration, electrons diffuse from the n-type side to the p-type side.
A transistor is a miniature electronic component that can do two different jobs. It can work either as an amplifier or a switch: When it works as an amplifier, it takes in a tiny electric current at one end (an input current) and produces a much bigger electric current (an output current) at the other.
Application: 1.)It is the process of rectifier as one of the part of DC Power Supplies. 4.)In cut-out circuits utilized for waveform era. PN junctions have been used as rectifiers in power supplies, detectors in RF,circuits, Zener diodes which are voltage regulators, clippers, LED's, PIN diodes are RF switches.
Carbon, silicon and germanium (germanium, like silicon, is also a semiconductor) have a unique property in their electron structure -- each has four electrons in its outer orbital. This allows them to form nice crystals. The four electrons form perfect covalent bonds with four neighboring atoms, creating a lattice.