3. INTRODUCTION
All existing transistors junctions with junction are P–N junction
Heterojunction,Scotty junction,MOSFET, MESFET.
The junctionless transistor (JLT) is a multigate FET with no PN nor N+N or
P+P junctions.
The device is basically a resistor in which the mobile carrier density can
be modulated by the gate.
Uniformly doped nanowire without junctions with a wrap-around gate.
No junctions and no doping concentration gradients.
They have near-ideal sub threshold slope,extremely low leakage currents,
and less degradation of mobility with gate voltage and temperature than
classical transistors.
4. INTRODUCTION
• …
• ,,
• Transistors are becoming so tiny that it is becoming
increasingly difficult to create high-quality junctions.
• In particular, it is very difficult to change the doping
concentration of a material over distances shorter than about
10 nm.
• Junctionless transistors could therefore help chipmakers
continue to make smaller and smaller devices.
5. STRUCTURE OF JUNCTIONLESS TRANSISTOR
Gated trans-resistor.
No junction.
Zero Doping concentration gradient.
Nano scale dimensions and high
6. FABRICATION PROCESS
Uniform Doping concentration.
Bulk conduction.
Beam lithography for nanowire and gates
For n-channeldevices
dopant: arsenic
channel concentration:
gate material: P+ polysilicon
11. Measured ID(VD) of N- and P-channel
junctionless transistors. L=1um, W=20nm
12. Measured ID(VG) of N- and P-channel
junctionless transistors. L=1um, W=20nm
ID, versus gate voltage, VG, for a drain voltage of +1 V in n-type and p-type
devices having a width of 30 nm and a length of 1 mm.
15. TYPES OF JUNCTIONLESS TRANSISTOR
Junctionless MuGFET:
• This device has no junctions, a simpler fabrication process,
less variability and better electrical property than classical
inversion mode.
Bulk Planar Junctionless Transistor (BPJLT):
• Highly scalable source–drain junction- free field-effect
transistor. It is thus junctionless in the source–channel–drain
path but needs a junction in the vertical direction for isolation
purposes
17. Adv & Dis
• the lateral extension of the S/D depletion charges in the channel region
are causing short-channel effects such as DIBL and degraded
subthreshold slope. These are absent in a JLT
• Further improvement of the short-channel effects can be obtained by
increasing the extension of the gate control deeper in the source and
drain regions using high-κ spacers.
• one disadvantage of conventional junctionless transistors is that they
suffer from poor short-channel control.
• junctionless devices have the potential to operate at faster and use less
energy than the conventional transistors used in today's
microprocessors.
18. • They have near-ideal sub threshold
slope,extremely low leakage currents, and
less degradation of mobility with gate
voltage and temperature than classical
transistors.
19. CONCLUSION
The devices have no junctions and are made in n+ or p+ silicon
nanowires.
The devices have full CMOS functionality
no junctions or doping gradients
less sensitive to thermal budget issues than regular CMOS devices.
a near-ideal subthreshold slope, close to60 mV/dec at room temperature
extremely low leakage currents.
Gated resistors exhibit less degradation of mobility than classical
transistors when the gate voltage is increased.
