# IV measurement

## IV measurement:

There are several parameters could extraxted from IV measurement such as threshould voltage and resistance :

### There are  several methods  to extract Vt,  such as extrapolation  in the linear region method, transconductance extrapolation method in the linear  region,  second-derivative method,  ratio method,  transition method,  second derivative logarithmic  method;  non-linear optimization method and integral method .All of these methods give slightly different values of Vt.  the transconductance extrapolation method, which  uses  a transconductance (gm) versus gate voltage curve. Vt is the gate voltage maximum slope at the point as shown in following figure • ## Subthreshold slope (S.S):

#### Cdm depletion layer capacitance. The theoretical minimum value for a MOSFET is 60mV/dec. next figure illustrate the curve between drain current and gate voltage whereit could determine subthershold slope . • ## Resistance:

### Where A= (µeff CoxWeff (Vg-Vt))-1

By drawing  the relation between channel length and resistance for different gate voltage the channel resistance is the y value where the lines are intersecting and the x value is ΔL.This

method is not accurate .Therefore, another method have been used to get more accurate value. Terada and Muta  pointed out another method to extract channel resistance which define

Rch=ƍ Leff/W             ƍ channel sheet resistance

Rm = Rsd + ƍ /W (L- ΔL)                               Rm= A + (ƍ/W) L

By drawing this equation for different gate voltages A  is  the  intercept point, and  the slop is ƍ/W. The slope of the relation between ƍ/W and A is ΔL and the intercept is the source drain
resistance. •   Kazuo Terada and Hiroki Muta ,A new method to determine effective MOSFET channel length ,  Japaness Journal of applied physics Vol.18,No,5,May1979.
•  K. Terada and H. Muta. "A New Method to Determine Effective MOSFET Channel Length". Jap. J. of Appl. Phys., 18:953{959, 1979.
• A. Ortiz-Condea , F.J. Garc ,S a ancheza, J.J. Liou b,1, A. Cerdeira c,M. Estrada c, Y.Yue d ,A review of recent MOSFET threshold voltage extraction methods,
Microelectronics eliability 42 (2002) 583–596.