And why does it matter? The intrinsic combination of ambi-polar device give can enhance on-to-off current ratio.
On off current ratio is often used in field effect transistors(FET).
It characterizes how much the difference between the on state current and off state current.Typically it is around 10^6-10^10.
hope can help you.
It's the ratio of the current in accumulation mode over the current in depletion mode
Current ON/OFF ratio is a characteristic of logic transistors. That is ratio of currents with Vgs=logic low and Vgs=logic high while Vds=constant and equals to maximum allowed voltage. These voltages may be different in CMOS(NMOS and PMOS) or TFETs. In an NMOS, logic low and high are 0,Vdd and Vds=Vdd. But in a TFET, Vds has a limit to avoid from tunneling.
For a device working as a switch it conducts an on current Ion when it is on and an off current Ioff when it is switched off. For an ideal switch the off current is ideally zero and the on current is limited by the external circuit.
In case of solid sate switches as the MOSFET transistor. the off current is not zero but it is a very small current. It is the current passing in the transistor when its gate to source voltage equals zero and VDS= VDD. It is observes as the transistor is scaled down, the off current increases appreciably because of the short channel effects with the most effective one is the induced barrier lowering.
The on current is limited by the W/L ratio, and the excess voltage of the transistor VGS-Vth in addition to the mobility. Therefore, because of this trend one has to maximize the Ion/Ioff ratio for static transistor losses.
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higher on to off ratio leads to better transistor as the leakage current may be reduced.
in digital applications transistors work like switches. higher on to off ratio means better switches.
In MOS transistors Ion and Ioff are used to on and off the FET by keeping the Ioff current as low as possible will gives us lesser leakage current and it is useful for low power applications.
On-off ratio is the ratio of the on-state and off-state current without any applied gate voltage (Vg). A high on-off ratio means a low leakage current i.e. an improved device performance. With reduced dimensionality, FETs (typically, MOSFETs) starts to show higher I_off due to short channel effect. This includes tunneling mechanisms like Klein tunneling. A lot of research works primarily focus on improving this on-off ratio which acts as a COP for the corresponding device.
this is one of the figure of merit, which helps in better understanding of the performance of the device. low leakage current or high on current increases the value of this ratio.
more the value ION/IOFF, more suitable the device will be for digital applications.
The on-off ratio, also known as the on-off current ratio, is a parameter that describes the ability to switch devices, such as field effect transistors, to control current. It is one of the key parameters of field effect transistors. Defined as the ratio of on-state current to off-state current.
How to measure "on current" for a HEMT (TEGFET). Even in log scale it is not ease to do it precisely.
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