9.8. PROBLEMS 483
Calculate and plotIDversusVDSfor 0 ≤VDS≤ 5 VandforVGSvalues of 0, 1, 2, 3
volts. Also, draw the locus of theVD(sat)points for each curve.
Problem 9.12Consider an idealp-channel MOSFET with the following parameters:
Channel width, Z =25μm
Channel mobility, μp = 250 cm^2 /V·s
Channel length, L =1. 0 μm
Oxide thickness, dox = 500A ̊
Threshold voltage, VT = − 0 .8V
Calculate and plotIDvs.VDSfor− 0. 5 ≤VDS≤ 0 Vforagatebiasof
VGS=0,− 1 ,− 2 ,− 3 V. Assume that the background doping is very small.
Problem 9.13In the text we used the criterion that inversion occurs whenVs=2φF.
Calculate the channel conductivity near the Si-Si0 2 interface for two MOS devices with
the following parameters:
Na =5× 1013 cm−^3 Na=5× 1015 cm−^3
μn = 600 cm^2 /V·s μn= 600 cm^2 /V·s
The problem shows the rather arbitrary way of defining the inversion condition.
Problem 9.14Ann-channel and ap-channel MOSFET have to be designed so that they
both have a saturated current of 5 mA when the gate-to-source voltage is 5 V for the
n-MOS and−5Vforthep-MOS. The other parameters of the devices are:
Oxide thickness, dox = 500A ̊
Electron mobility, μn = 500 cm^2 /V·s
Hole mobility, μp = 300 cm^2 /V·s
VTfor then-MOS, =+0.7V
VTfor thep-MOS, = − 0 .7V
What is theZ/Lratio for then-MOSFET and thep-MOSFET?
Problem 9.15Ann-channel MOSFET has the following parameters:
Oxide thickness, dox = 500A ̊
p-type doping, Na =10^16 cm−^3
Flat band voltage, Vfb = − 0 .5V
Channel length, L =1. 0 μm
Channel width, Z =15μm
Channel mobility, μn = 500 cm^2 /V·s
Plot
√
ID(sat)versusVGSover the range 0 ≤ID(sat)≤ 1 mAfor the source-to-body
voltage ofVSB=0,1,2V.
