Presentation is loading. Please wait.

Presentation is loading. Please wait.

President UniversityErwin SitompulSDP 6/1 Dr.-Ing. Erwin Sitompul President University Lecture 6 Semiconductor Device Physics

Published byFelix McLaughlin Modified over 9 years ago

Similar presentations

Presentation on theme: "President UniversityErwin SitompulSDP 6/1 Dr.-Ing. Erwin Sitompul President University Lecture 6 Semiconductor Device Physics"— Presentation transcript:

1 President UniversityErwin SitompulSDP 6/1 Dr.-Ing. Erwin Sitompul President University Lecture 6 Semiconductor Device Physics http://zitompul.wordpress.com

2 President UniversityErwin SitompulSDP 6/2 Majority carriers Majority carriers Qualitative Derivation Chapter 6pn Junction Diodes: I-V Characteristics

3 President UniversityErwin SitompulSDP 6/3 Current Flow in a pn Junction Diode Chapter 6pn Junction Diodes: I-V Characteristics When a forward bias (V A > 0) is applied, the potential barrier to diffusion across the junction is reduced. Minority carriers are “injected” into the quasi-neutral regions  Δn p > 0, Δp n > 0. Minority carriers diffuse in the quasi-neutral regions, recombining with majority carriers.

4 President UniversityErwin SitompulSDP 6/4 Ideal Diode: Assumptions Chapter 6pn Junction Diodes: I-V Characteristics Steady-state conditions. Non-degenerately doped step junction. One-dimensional diode. Low-level injection conditions prevail in the quasi-neutral regions. No processes other than drift, diffusion, and thermal R–G take place inside the diode.

5 President UniversityErwin SitompulSDP 6/5 Current Flow in a pn Junction Diode Chapter 6pn Junction Diodes: I-V Characteristics Current density J = J N (x) + J P (x) J N (x) and J P (x) may vary with position, but J is constant throughout the diode. Yet an additional assumption is now made, that thermal recombination-generation is negligible throughout the depletion region  J N and J P are therefore determined to be constants independent of position inside the depletion region.

6 President UniversityErwin SitompulSDP 6/6 n-sidep-side Carrier Concentrations at –x p, +x n Chapter 6pn Junction Diodes: I-V Characteristics Consider the equilibrium carrier concentrations at V A = 0: If low-level injection conditions prevail in the quasi-neutral regions when V A  0, then:

7 President UniversityErwin SitompulSDP 6/7 “Law of the Junction” Chapter 6pn Junction Diodes: I-V Characteristics The voltage V A applied to a pn junction falls mostly across the depletion region (assuming that low-level injection conditions prevail in the quasi-neutral regions). Two quasi-Fermi levels is drawn in the depletion region:

8 President UniversityErwin SitompulSDP 6/8 n-sidep-side Excess Carrier Concentrations at –x p, x n Chapter 6pn Junction Diodes: I-V Characteristics

9 President UniversityErwin SitompulSDP 6/9 Example: Carrier Injection Chapter 6pn Junction Diodes: I-V Characteristics A pn junction has N A =10 18 cm –3 and N D =10 16 cm –3. The applied voltage is 0.6 V. a)What are the minority carrier concentrations at the depletion-region edges? b)What are the excess minority carrier concentrations?

10 President UniversityErwin SitompulSDP 6/10 Excess Carrier Distribution Chapter 6pn Junction Diodes: I-V Characteristics From the minority carrier diffusion equation, We have the following boundary conditions: For simplicity, we develop a new coordinate system: Then, the solution is given by: L P : hole minority carrier diffusion length

11 President UniversityErwin SitompulSDP 6/11 Excess Carrier Distribution Chapter 6pn Junction Diodes: I-V Characteristics New boundary conditions From the x’ → ∞, From the x’ → 0, Therefore Similarly,

12 President UniversityErwin SitompulSDP 6/12 n-side p-side pn Diode I–V Characteristic Chapter 6pn Junction Diodes: I-V Characteristics

13 President UniversityErwin SitompulSDP 6/13 pn Diode I–V Characteristic Chapter 6pn Junction Diodes: I-V Characteristics Shockley Equation, for ideal diode I 0 can be viewed as the drift current due to minority carriers generated within the diffusion lengths of the depletion region

14 President UniversityErwin SitompulSDP 6/14 I 0 can vary by orders of magnitude, depending on the semiconductor material, due to n i 2 factor. In an asymmetrically doped pn junction, the term associated with the more heavily doped side is negligible. If the p side is much more heavily doped, If the n side is much more heavily doped, Diode Saturation Current I 0 Chapter 6pn Junction Diodes: I-V Characteristics

15 President UniversityErwin SitompulSDP 6/15 Diode Carrier Currents Chapter 6pn Junction Diodes: I-V Characteristics Total current density is constant inside the diode Negligible thermal R-G throughout depletion region  dJ N /dx = dJ P /dx = 0

16 President UniversityErwin SitompulSDP 6/16 Excess minority carriers Excess minority carriers Carrier Concentration: Forward Bias Chapter 6pn Junction Diodes: I-V Characteristics Law of the Junction Low level injection conditions

17 President UniversityErwin SitompulSDP 6/17 Carrier Concentration: Reverse Bias Chapter 6pn Junction Diodes: I-V Characteristics Deficit of minority carriers near the depletion region. Depletion region acts like a “sink”, draining carriers from the adjacent quasineutral regions

18 President UniversityErwin SitompulSDP 6/18 Forward-bias current Reverse-bias current “Breakdown” “Slope over” No saturation Smaller slope Deviations from the Ideal I-V Behavior Chapter 6pn Junction Diodes: I-V Characteristics Si pn-junction Diode, 300 K.

19 President UniversityErwin SitompulSDP 6/19 This time no homework. Prepare well for midterm examination. Homework Chapter 6pn Junction Diodes: I-V Characteristics

Download ppt "President UniversityErwin SitompulSDP 6/1 Dr.-Ing. Erwin Sitompul President University Lecture 6 Semiconductor Device Physics"

Similar presentations

Chapter 6-2. Carrier injection under forward bias

Chapter 6-2. Carrier injection under forward bias
Chapter 6-1. PN-junction diode: I-V characteristics

Chapter 6-1. PN-junction diode: I-V characteristics
Semiconductor Device Physics Lecture 8 PN Junction Diodes: I-V Characteristics Dr. Gaurav Trivedi, EEE Department, IIT Guwahati.

Semiconductor Device Physics Lecture 8 PN Junction Diodes: I-V Characteristics Dr. Gaurav Trivedi, EEE Department, IIT Guwahati.
Lecture 5 OUTLINE PN Junction Diodes I/V Capacitance Reverse Breakdown

Lecture 5 OUTLINE PN Junction Diodes I/V Capacitance Reverse Breakdown
PN Junction: Physical and Mathematical Description of Operation Dragica Vasileska Professor Arizona State University PN Junctions – General Considerations.

PN Junction: Physical and Mathematical Description of Operation Dragica Vasileska Professor Arizona State University PN Junctions – General Considerations.
ECE 663 P-N Junctions. ECE 663 So far we learned the basics of semiconductor physics, culminating in the Minority Carrier Diffusion Equation We now encounter.

ECE 663 P-N Junctions. ECE 663 So far we learned the basics of semiconductor physics, culminating in the Minority Carrier Diffusion Equation We now encounter.
© Electronics ECE 1312 Recall-Lecture 2 Introduction to Electronics Atomic structure of Group IV materials particularly on Silicon Intrinsic carrier concentration,

© Electronics ECE 1312 Recall-Lecture 2 Introduction to Electronics Atomic structure of Group IV materials particularly on Silicon Intrinsic carrier concentration,
5.1 Introduction 5.2 Equilibrium condition 5.2.1 Contact potential

5.1 Introduction 5.2 Equilibrium condition Contact potential
PN Junction Diodes.

PN Junction Diodes.
Figure 2.1 The p-n junction diode showing metal anode and cathode contacts connected to semiconductor p-type and n-type regions respectively. There are.

Figure 2.1 The p-n junction diode showing metal anode and cathode contacts connected to semiconductor p-type and n-type regions respectively. There are.
COMSATS Institute of Information Technology Virtual campus Islamabad

COMSATS Institute of Information Technology Virtual campus Islamabad
Semiconductor pn junctions. semiconductor pn junction context Figure 8.1-2 pn junction representations.

Semiconductor pn junctions. semiconductor pn junction context Figure pn junction representations.
Semiconductor Device Physics Lecture 6 Dr. Gaurav Trivedi, EEE Department, IIT Guwahati.

Semiconductor Device Physics Lecture 6 Dr. Gaurav Trivedi, EEE Department, IIT Guwahati.
EE105 Fall 2007Lecture 3, Slide 1Prof. Liu, UC Berkeley Lecture 3 ANNOUNCEMENTS HW2 is posted, due Tu 9/11 TAs will hold their office hours in 197 Cory.

EE105 Fall 2007Lecture 3, Slide 1Prof. Liu, UC Berkeley Lecture 3 ANNOUNCEMENTS HW2 is posted, due Tu 9/11 TAs will hold their office hours in 197 Cory.
Lecture 15, Slide 1EECS40, Fall 2004Prof. White Lecture #15 OUTLINE The pn Junction Diode -- Uses: Rectification, parts of transistors, light-emitting.

Lecture 15, Slide 1EECS40, Fall 2004Prof. White Lecture #15 OUTLINE The pn Junction Diode -- Uses: Rectification, parts of transistors, light-emitting.
Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 1 Chapter IV June 14, 2015June 14, 2015June 14, 2015 P-n Junction.

Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 1 Chapter IV June 14, 2015June 14, 2015June 14, 2015 P-n Junction.
Department of EECS University of California, Berkeley EECS 105 Fall 2003, Lecture 9 Lecture 9: PN Junctions Prof. Niknejad.

Department of EECS University of California, Berkeley EECS 105 Fall 2003, Lecture 9 Lecture 9: PN Junctions Prof. Niknejad.
OUTLINE pn junction I-V characteristics Reading: Chapter 6.1

OUTLINE pn junction I-V characteristics Reading: Chapter 6.1
EE105 Fall 2011Lecture 6, Slide 1Prof. Salahuddin, UC Berkeley Lecture 6 OUTLINE PN Junction Diodes – Reverse Breakdown – Large and Small signal models.

EE105 Fall 2011Lecture 6, Slide 1Prof. Salahuddin, UC Berkeley Lecture 6 OUTLINE PN Junction Diodes – Reverse Breakdown – Large and Small signal models.
EE105 Fall 2007Lecture 4, Slide 1Prof. Liu, UC Berkeley Lecture 4 OUTLINE Bipolar Junction Transistor (BJT) – General considerations – Structure – Operation.

EE105 Fall 2007Lecture 4, Slide 1Prof. Liu, UC Berkeley Lecture 4 OUTLINE Bipolar Junction Transistor (BJT) – General considerations – Structure – Operation.

Similar presentations

Ads by Google