What is the properties of ohmic contact?
The Ohmic contact is a low resistance junction (non-rectifying) provides current conduction from metal to semiconductor and vice versa. Theoretically speaking the current should increase/ decrease linearly with the applied voltage.
What is difference between ohmic contact and Schottky contact?
Conclusion. Overall, for a metal and an n-type semiconductor, a rectifying Schottky contact is formed when ΦM>ΦS, and an Ohmic contact is formed when ΦM<ΦS. Similarly, for a metal and an p-type semiconductor, the MS contact will be rectifying Schottky when ΦM<ΦS, and Ohmic contact when ΦM>ΦS.
What does ohmic contact mean?
An ohmic contact is a non-rectifying electrical junction: a junction between two conductors that has a linear current–voltage (I-V) curve as with Ohm’s law. By contrast, a junction or contact that does not demonstrate a linear I-V curve is called non-ohmic.
What are ohmic and Schottky contacts with reference to metal semiconductor junction?
A Schottky junction is formed when the semiconductor has a lower work func- tion than the metal. When the semiconductor has a higher work function the junction formed is called the Ohmic junction.
What is the contact potential?
a difference in electric potentials arising between two bodies that are in contact and in thermo-dynamic equilibrium. The value of the contact potential is equal to the difference in work functions divided by the charge of an electron. …
Why Aluminium is preferred as a metal for ohmic contacts because?
Aluminum is a good ohmic contact to n-type CdS (Mead et al, 1964) because its work function is smaller than the CdS electron affinity (Michaelson, 1977; Brillson, 1978; Ebina et al, 1982) and the substitution of Cd by Al gives an electron that increases the doping concentration near the interface.
What are Schottky contacts?
The rectifying contact that occur between a metal and a lightly doped semiconductor. b) Ideal energy -band diagram of a metal and n-type semiconductor junction. …
What are ohmic and rectifying contacts?
A rectifying contact is similar to a pn junction inasmuch as it allows a large current in one voltage polarity and a much smaller current in the other. A contact is said to be ohmic, i.e., non-rectifying, if it exhibits negligible resistance to current in both voltage polarities.
What causes contact potential?
a difference in electric potentials arising between two bodies that are in contact and in thermo-dynamic equilibrium. As a result, the conductors acquire electric charges of opposite sign, which causes the appearance of an electric field that impedes the flow of electrons. …
What is contact potential of a pn junction?
Thus, an electric field is formed going from the n-side to the p-side and there is a built-in potential, from the p to the n side. This potential is called the junction potential or contact potential.
What do you mean by the Schottky and ohmic contacts?
Schottky Contacts make good diodes, and can even be used to make a kind of transistor, but for getting signals into and out of a semiconductor device, we generally want a contact that is Ohmic. Ohmic contacts conduct the same for both polarities. (They obey Ohm’s Law).
What is Schottky barrier potential?
A Schottky barrier, named after Walter H. Schottky, is a potential energy barrier for electrons formed at a metal-semiconductor junction [17]. Schottky barriers have rectifying characteristics, and then they are suitable for use as diodes.
How to make an ohmic contact between metal and semiconductor?
The way to achieve such a contact is by doping the semiconductor heavily enough that tunneling is possible. It is usual to heavily dope the Si regions N+ or P+ so that an ohmic contact is insured. Suppose Nd (or Na) in the semiconductor is very large. Then the depletion region width at the metal – semiconductor interface Xd= 2Kεoφi q Nd
Why do we need ohmic and Schottky contacts?
Almost all metal-semiconductor junctions will exhibit some of this rectifying behavior.Schottky Contacts make good diodes, and can even be used to make a kind of transistor, but for getting signals into and out of a semiconductor device, we generally want a contact that is Ohmic. Ohmic contacts conduct the same for both polarities.
How is the contact potential between two metals related?
Because electrons move from Mo to Pt a net positive charge develops on the Mo side and a net negative charge on the Pt side. Thus, a contact potential is developed at equilibrium between the two metals. This contact potential is related to the di\erence in the work functions, and is shown in \\fgure 2.
How are Fermi levels related to metal contacts?
If a metal with a workfunction less than that of a given p-type material were used to contact the p-type semiconductor, then a dipole oriented positive in the metal and negative in the semiconductor would have to result to equate the Fermi levels in TE.