What is metal-semiconductor work function?
In a semiconductor, the work function is sensitive to the doping level at the surface of the semiconductor. Since the doping near the surface can also be controlled by electric fields, the work function of a semiconductor is also sensitive to the electric field in the vacuum.
How do you determine the work function of a metal?
The work function is the minimum energy required to take out one electron through the surface. It can be measured by analyzing the slowest electrons emitted from the substrate applied with excess energy.
Why do we study metal-semiconductor junction?
Metal–semiconductor junctions are crucial to the operation of all semiconductor devices. Usually an ohmic contact is desired, so that electrical charge can be conducted easily between the active region of a transistor and the external circuitry.
How many types of metal-semiconductor functions are there?
two types
Basically, there are two types of MS contacts that are widely used in semiconductor devices: Rectifying Schottky Diodes. Non-rectifying Ohmic contact.
Why do metals have different work functions?
Different metals have different values of work function because of difference in their electronegativity. The least electronegative (or most electropositive) metal would let go of its valence electron very easily compared to those metals with higher values of electronegativity.
What is semiconductor metal?
Semiconductors are materials which have a conductivity between conductors (generally metals) and nonconductors or insulators (such as most ceramics). Semiconductors can be pure elements, such as silicon or germanium, or compounds such as gallium arsenide or cadmium selenide.
What metals are in semiconductors?
The behavior of charge carriers, which include electrons, ions, and electron holes, at these junctions is the basis of diodes, transistors, and most modern electronics. Some examples of semiconductors are silicon, germanium, gallium arsenide, and elements near the so-called “metalloid staircase” on the periodic table.
Which metal has least work function?
cesium
The work function (ϕo) depends on the properties of the metal and the nature of its surface. The work function of platinum is the highest while it is the lowest for cesium.
Which diode uses a metal-semiconductor junction?
Schottky diode
The Schottky diode (named after the German physicist Walter H. Schottky), also known as Schottky barrier diode or hot-carrier diode, is a semiconductor diode formed by the junction of a semiconductor with a metal.
What is metal oxide junction?
The ob- vious insulator for silicon is its natural oxide (silicon oxide: SiO2), thus the junction is called. metal-oxide-semiconductor (MOS). The oxidation of the crystalline silicon typically occurs in an atmosphere of either oxygen or water. vapor kept at a temperature between 850◦C and 1100◦C.
What is the difference between metals and semiconductors?
Metals are conductors and therefore they carry high amount of electricity. Semiconductors have less electrical conductivity than metals. In metals electrons carry out the current. But in semiconductors, current is carried out by the flow of electrons of positively charged holes.
Which metal has high work function?
The work function of platinum is the highest while it is the lowest for cesium. The work function for platinum is 5.65 eV. The work function for cesium is 2.14 eV.
How a metal-semiconductor junction can be made to behave as a rectifying junction?
By varying the type of metal or the semiconductor doping level, the junction can be made into a rectifying or a nonrectifying junction. Rectifying junctions preferentially permit current to flow in one direction versus the other.