What is TLM testing?
Transmission line method (TLM) a) the measuring position, and b) test structure for determining the contact resistance (where R – the sheet resistance, k – front contact length, L – width of contact, d – distance between contacts).
What is difference between ohmic contact and Schottky contact?
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 are Schottky contacts?
The rectifying contact that occur between a metal and a lightly doped semiconductor.
How do you measure TLM?
- Contact Resistance.
- The contact resistance is usually not well defined.
- R T = 2 R C + R sheet L W , ( Rsemi = R sheet L W )
- Contact Resistivity.
- Current Crowding.
- L T = ρ C R sheet.
- A typical arrangement for a TLM test pattern is shown below.
What is the cause of contact resistance?
Contact resistance is the resistance to current flow, due to surface conditions and other causes, when contacts are touching one another (in the closed condition of the device). This can occur between contacts of: Breakers. Contactors.
How do you reduce contact resistance?
These errors appear to be largely eliminated by use of a high conductivity thermal grease to coat the probe. In materials that have particles substantially larger than the probe, contact resistance errors can be greater than 50%. Use of the thermal grease decreases errors, even in these materials, to a few percent.
What is meant by Schottky barrier?
A Schottky barrier refers to a metal-semiconductor contact having a large barrier height (i.e. and low doping concentration that is less than the density of states in the conduction band or valence band. The potential barrier between the metal and the semiconductor can be identified on an energy band diagram.
What is the range of contact resistance?
Measurements of contact resistivities for typical solar cell metallizations using this technique are reported to be in the mid 10 -6 Ω-cm 2 range. The relative importance of contact resistance compared to other sources of power loss in a solar cell is determined for a typical contact system.
How can contact resistance be reduced?
found that contact annealing can minimize the contact resistance and eliminate the non-ideal current–voltage curves arising from gated Schottky contacts11.