Ohmic contact: Difference between revisions

Latest revision as of 05:27, 16 February 2025

An electrical junction that obeys Ohm's law

Ohmic contact[edit]

An ohmic contact is a region on a semiconductor device that has been engineered to have a very low resistance and allows current to pass through it easily, following Ohm's law. This type of contact is crucial in semiconductor devices as it ensures efficient current injection or extraction without significant voltage drop.

Characteristics[edit]

Ohmic contacts are characterized by their linear current-voltage (I-V) relationship, meaning that the current through the contact is directly proportional to the voltage across it. This linearity is essential for the predictable performance of electronic devices.

Formation[edit]

The formation of an ohmic contact involves creating a metal-semiconductor junction that does not rectify current. This can be achieved by:

Doping: Increasing the doping concentration at the contact region to reduce the barrier height.
Metal selection: Choosing metals with appropriate work functions to align with the semiconductor's energy bands.
Annealing: Applying heat treatment to improve the contact interface by reducing defects and forming intermetallic compounds.

Applications[edit]

Ohmic contacts are used in various semiconductor devices, including:

These contacts are essential for ensuring that the devices operate efficiently and reliably.

Challenges[edit]

Creating a perfect ohmic contact can be challenging due to:

Material compatibility: Ensuring that the metal and semiconductor materials are compatible and do not form unwanted compounds.
Surface preparation: Achieving a clean and smooth surface to minimize contact resistance.
Thermal stability: Ensuring that the contact remains stable under operating conditions.

Related pages[edit]

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-'''Ohmic contact''' refers to a type of electrical junction in which the current through the contact is directly proportional to the applied voltage. This behavior follows [[Ohm's Law]], which states that the current (I) through a conductor between two points is directly proportional to the voltage (V) across the two points, and inversely proportional to the resistance (R) of the conductor. Ohmic contacts are crucial in the design and operation of various electronic devices, including [[semiconductors]], [[transistors]], and [[diodes]], as they ensure efficient current flow with minimal voltage drop and energy loss.
+{{Short description|An electrical junction that obeys Ohm's law}}
-==Characteristics==
+== Ohmic contact ==
-Ohmic contacts are characterized by their linear current-voltage (I-V) relationship, low contact resistance, and non-rectifying behavior. Unlike [[Schottky contacts]], which exhibit a rectifying (diode-like) I-V characteristic, ohmic contacts allow current to flow equally well in both directions. This is essential for the proper functioning of electronic components that require a stable and predictable electrical connection.
+An '''ohmic contact''' is a region on a semiconductor device that has been engineered to have a very low resistance and allows current to pass through it easily, following [[Ohm's law]]. This type of contact is crucial in semiconductor devices as it ensures efficient current injection or extraction without significant voltage drop.
-==Materials and Fabrication==
+[[File:IEEE_315-1975_(1993)_8.2.1.svg|thumb|right|Schematic representation of an ohmic contact]]
-The creation of an ohmic contact involves the selection of appropriate materials and fabrication techniques that minimize the barrier for electron flow at the interface between a metal and a semiconductor. Metals with a high work function are typically used for making ohmic contacts to p-type semiconductors, while metals with a low work function are chosen for n-type semiconductors. The goal is to achieve a match or an overlap in the energy bands of the metal and the semiconductor, facilitating the free flow of charge carriers across the contact.
-Fabrication methods for ohmic contacts include thermal alloying, sputtering, and electron-beam evaporation, among others. The choice of method depends on the materials involved, the required contact properties, and the specific application. Post-fabrication annealing is often performed to improve the contact's electrical characteristics by reducing its resistance and enhancing its stability.
+== Characteristics ==
+Ohmic contacts are characterized by their linear current-voltage (I-V) relationship, meaning that the current through the contact is directly proportional to the voltage across it. This linearity is essential for the predictable performance of electronic devices.
-==Applications==
+== Formation ==
-Ohmic contacts are integral to the operation of a wide range of electronic devices. In [[semiconductor devices]], they provide the necessary electrical connections for the injection of charge carriers into the active regions. In [[solar cells]], ohmic contacts are used to collect and transport charge carriers generated by light absorption. Similarly, in [[light-emitting diodes (LEDs)]], ohmic contacts are essential for the injection of electrons and holes into the semiconductor material, where their recombination produces light.
+The formation of an ohmic contact involves creating a metal-semiconductor junction that does not rectify current. This can be achieved by:
-==Challenges==
+* '''Doping''': Increasing the doping concentration at the contact region to reduce the barrier height.
-Designing and fabricating ohmic contacts can present several challenges, particularly for new semiconductor materials with unique properties. Achieving low contact resistance, maintaining stability under operating conditions, and preventing degradation over time are critical considerations. Additionally, the development of ohmic contacts for emerging technologies, such as [[organic semiconductors]] and [[two-dimensional materials]], requires innovative approaches to material selection and processing.
+* '''Metal selection''': Choosing metals with appropriate work functions to align with the semiconductor's energy bands.
+* '''Annealing''': Applying heat treatment to improve the contact interface by reducing defects and forming intermetallic compounds.
-==Conclusion==
+== Applications ==
-Ohmic contacts play a vital role in the performance and reliability of electronic devices by ensuring efficient and stable current flow. Advances in materials science and fabrication technologies continue to improve the characteristics of ohmic contacts, enabling the development of more efficient and compact electronic components.
+Ohmic contacts are used in various semiconductor devices, including:
+* [[Diode]]s
+* [[Transistor]]s
+* [[Integrated circuit]]s
+These contacts are essential for ensuring that the devices operate efficiently and reliably.
+== Challenges ==
+Creating a perfect ohmic contact can be challenging due to:
+* '''Material compatibility''': Ensuring that the metal and semiconductor materials are compatible and do not form unwanted compounds.
+* '''Surface preparation''': Achieving a clean and smooth surface to minimize contact resistance.
+* '''Thermal stability''': Ensuring that the contact remains stable under operating conditions.
+== Related pages ==
+* [[Schottky contact]]
+* [[Semiconductor device]]
+* [[Ohm's law]]
-[[Category:Electrical engineering]]
 [[Category:Semiconductor devices]]
-{{electronics-stub}}