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					                Requirements Document For




Java Applets – For Physical Electronics.



        Submitted to: Professor Stephen E.Saddow.


             ECE 6243:Physical Electronics
    Department of Electrical and Computer Engineering
               Mississippi State University
           Mississippi State, Mississippi 39762

                        October 2,2000




                         Submitted by:


             Team Leader: Ramya Chandrasekaran
              Team Members: Pujita Pinnamaneni
               Faculty Advisor: Dr.Steve Saddow
       Department of Electrical and Computer Engineering
                  Mississippi State University

                  email: rc1@ece.msstate.edu
                    pp2@ece.msstate.edu
                                  Executive Summary
       The Internet has the potential to greatly assist in the educational process since
students may learn in a more efficient way. This is due to the graphical interface along
with the interactive animation capabilities of modern Internet applications. JAVA applets
(mathematical applications) have further enhanced this internet-based learning as applets
are used to create user-friendly applications, which can be posted on the web and are
easily accessible. We aim at designing applets to enable students to have a better
knowledge about the characteristics of the Schottky Diodes before they work with these
diodes physically.

         It is possible to have metal to semiconductor contacts that would behave like a
rectifier – allowing current to flow in one direction and not the other. These are referred
to as Schottky barrier junctions. An Schottky barrier is created by the intimate contact of
a metal and a semiconductor.

        An schottky diode is a special type of diode with a very low forward-voltage
drop. When current flows through a diode, it has some internal resistance to that current
flow, which causes a small voltage drop across the diode terminals. A normal Si pn
junction diode has between 0.7-1.7 V drop, while an schottky diode voltage drop is
between approximately 0.15-0.45 V. This lower voltage drop translates into higher
system efficiency but at the cost of higher reverse leakage currents due to the lower
barrier to this type of current flow.

        The least complex power device is the Schottky rectifier. An schottky diode
consists of an n+-doped substrate with a backside ohmic contact, a lightly doped n-
epitaxial drift layer and a topside Schottky contact with a high resistivity edge
termination to suppress surface leakage currents. The schottky diode is fabricated by
evaporating a high work function metal, such as titanium, nickel, or gold, onto the
epitaxial layer to form the schottky contact and by depositing a ohmic contact metal onto
the back of the n+ substrate. The order of these depositions must be reversed to
accommodate annealing of the ohmic contact. The high resistivity edge termination is
achieved by implanting an inert species, such as argon, which damages the exposed
semiconductor causing a high resistivity region. This process is self-aligned to the
schottky contact because the schottky metal acts as a mask preventing damage under the
contact.

       In Schottky barrier junctions the carriers used for electrical conduction are the
majority carrier of the semiconductor. Since electrons have higher mobility, n-type
schottky barrier contact is more common than the p-type schottky barrier junction.

       Studying the physical characteristics of the Schottky diodes, we will try to
implement the carrier concentration vs. the temperature characteristics of the schottky
diode in form of applets that will make it easier for us to understand the variation in
behavior of an schottky diode with changes in temperature and carrier concentration.
Problem.
Trying to analyze the physical properties of a schottky diodes is a tedious process which
involved complex circuit designing and time consuming process of analyzing the
characteristics of the diodes before proceeding to the main circuit
.
Our idea about creating these applets is to enable us to figure out the actual behavior and
characteristics of diode in a more efficient and a comfortable way without spending much
time on designing circuits just to learn the characteristics of a diode.

The visual representation of the characteristics of the diodes gives us a better way of
understanding and analyzing the features of these diodes. Visual simulation also helps us
to test a wide range of values, which is usually a very time consuming process when done
practically.




Objectives.
Easy Study:

We are designing these applets for educational purpose that enables students to have fun
while learning the concepts of schottky diodes.

Faster approach:

As Internet is a comfortable way to reach one and all we are trying to help
students have an easy access to the characteristics of a schottky diodes.

Cost:

Since we are simulating the characteristics of schottky diodes on the computer
we are trying to get down the product cost in the laboratories that would cost
while learning these characteristics by implementing them practically.

Self-Analyzing:

Students can analyze the characteristics of the schottky diodes by entering
various  values   as  parameters    and    view  the    results immediately.
                                   References
1.The potential of fast high voltage Sic Diodes-Heinz Mitlehner, Wolfgang Bartsch,
  Manfred Bruckmann, Karl Otto Dohnke, Ulrich Weinert

2.The Effect of Heat treatment on Au Schottky contacts on B-SiC-Dimitris
  E.Ioannou, Nick A.Papanicolaou, Paul E.Nordquist, JR.

3.Au-SiC Schottky Barrier Diodes-S.Y.Wu, R.B.Campbell

4.Pt and Pt SiC Schottky contacts on n-type B-SiC-N.A.Papanicolaou, A.Christou,
  and M.L.Gipe

5.High-Voltage Ni-and Pt-Sic Schottky Diodes utilizing Metal          field   plate
  Termination-Vik Saxena, Jian Nong (Jim) Su, and Andrew J.Steckl

6.Schottky Barrier Diodes-Dallas Morisette, Mitch McGlothlin, J.A.Cooper, Jr., and
  M.R.Melloch

7.Planar Terminations in 4H-SiC Schottky Diodes with low leakage and high yields-
  R.Singh and J.W.Palmour

8.Silicon Carbide High-Power Devices-Charles E.Weitzel, John W.Palmour, Calvin
  H.Carter, Jr., Karen Moore, Kevin J.Nordquist, Scott Allen, Christine Thero, and
  Mohit Bhatnagar

9.A 3 kV Schottky barrier diode in 4H-SiC-Q.Wahab,T.Kimoto, A.Ellison, C.Hallin,
  M.Tuominen, R.Yakimova, A.Henry, J.P.Bergman, and E.Janzen

10.Al/Ti Schottky Barrier Diodes with the Gaurd -Ring Termination for 6H-SiC-
   Katsunori Ueno, Tatsuo Urushidani, Kouichi Hashimoto, and Yasukazu Seki

11.Surface Barrier Diodes on Silicon Carbide-S.H.Hagen

12.Efficient Power      Schottky   Rectifiers   of   4H-SiC-A.Itoh,T.Kimoto    and
   H.Matsunami

13. Schottky Barrier diodes on 3C-SiC-S.Yoshida,K.Sasaki, E.Sakuma, S.Misawa,
   and S.Gonda

				
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