ECE 875: Electronic Devices
description
Transcript of ECE 875: Electronic Devices
![Page 1: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/1.jpg)
ECE 875:Electronic Devices
Prof. Virginia AyresElectrical & Computer EngineeringMichigan State [email protected]
![Page 2: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/2.jpg)
VM Ayres, ECE875, S14
Lecture 27, 19 Mar 14
Chp 04: metal-insulator-semiconductor junction: GATES
Examples
![Page 3: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/3.jpg)
VM Ayres, ECE875, S14
![Page 4: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/4.jpg)
Chp. 01: Si
Chp. 02: pn
Chp. 03: Interconnect
Chp. 04: MOS: Gate
VM Ayres, ECE875, S14
![Page 5: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/5.jpg)
p-type Si
VM Ayres, ECE875, S14
Use energy band diagram to find:
![Page 6: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/6.jpg)
p-type Si
VM Ayres, ECE875, S14
Use energy band diagram to find:
Electron concentration in channel
V requirements: battery = $
E –field/Vi across the insulator: breakdown not good
![Page 7: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/7.jpg)
Q(x)
E (x)
V (x)
Everything else
Usual approach:
VM Ayres, ECE875, S14
![Page 8: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/8.jpg)
= d E dx
∞ means deep in substrate
The total charge density is
The Electric field is a function of the charge density.
The potential is proportional to the Electric field
The surface charge is:
Usual approach:
VM Ayres, ECE875, S14
![Page 9: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/9.jpg)
Example 01 (will be a continuing problem):
+
VM Ayres, ECE875, S14
![Page 10: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/10.jpg)
Answer:
VM Ayres, ECE875, S14
= 2.32 x 104 cm-3
In forward bias:
= 38.6 V-1 @ r.t.
![Page 11: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/11.jpg)
Example: what is the electron concentration at x = 0?
VM Ayres, ECE875, S14
= 2.32 x 104 cm-3
In forward bias:
= 38.6 V-1 @ r.t.
![Page 12: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/12.jpg)
Answer: need p = p(x)
VM Ayres, ECE875, S14
= 2.32 x 104 cm-3
In forward bias:
= 38.6 V-1 @ r.t.
![Page 13: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/13.jpg)
Can find potential p(at x=0) using strong inversion condition:
2 x Bp =
VM Ayres, ECE875, S14s = p(x=0)
![Page 14: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/14.jpg)
Example:
Evaluate s in strong inversion condition for example problem 01 with NA = 4 x 1015 cm-3
VM Ayres, ECE875, S14
![Page 15: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/15.jpg)
Answer:
VM Ayres, ECE875, S14
p(x = 0) =
![Page 16: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/16.jpg)
Q(x)
E (x)
V (x)
Everything else
To find p(x) (and therefore concentration) must use this approach:
VM Ayres, ECE875, S14
Will get E -field first and also wanted to know that
![Page 17: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/17.jpg)
Metal = battery potential: V
p-type Semiconductor potential: p(x)
New: the potential drop across the (ideal) insulator Vi
Semiconductor surface potential:s = p(x=0)
Electric field and potentials: in inversion:
VM Ayres, ECE875, S14
Breakdown info here concentration info here
![Page 18: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/18.jpg)
VM Ayres, ECE875, S14
![Page 19: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/19.jpg)
LD : the Debye length
VM Ayres, ECE875, S14
![Page 20: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/20.jpg)
Example:
VM Ayres, ECE875, S14
![Page 21: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/21.jpg)
Answer:
VM Ayres, ECE875, S14
![Page 22: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/22.jpg)
Take the square root of E 2 in eq’n 10 and use p(x=0) = s to evaluate:
VM Ayres, ECE875, S14
Can easily find E (x=0) = E s:
![Page 23: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/23.jpg)
VM Ayres, ECE875, S14
Can easily find Q(x=0) = Qs:
![Page 24: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/24.jpg)
Example:
VM Ayres, ECE875, S14
Evaluate Qs for s = 0.67 V
![Page 25: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/25.jpg)
VM Ayres, ECE875, S14
Answer:
![Page 26: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/26.jpg)
VM Ayres, ECE875, S14
![Page 27: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/27.jpg)
VM Ayres, ECE875, S14
![Page 28: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/28.jpg)
VM Ayres, ECE875, S14
s
![Page 29: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/29.jpg)
VM Ayres, ECE875, S14
Note that an important part of the concentration we’d like to know could be defined as charge/area under the Gate (different than usual units)
![Page 30: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/30.jpg)
Example:
VM Ayres, ECE875, S14
![Page 31: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/31.jpg)
Answer:
VM Ayres, ECE875, S14
![Page 32: ECE 875: Electronic Devices](https://reader035.fdocuments.in/reader035/viewer/2022062723/56813bca550346895da4f5b9/html5/thumbnails/32.jpg)
VM Ayres, ECE875, S14