1. JAVA Applets for Physical Electronics.
Metal
Semiconductor
Metal
Semiconductor
Depletion Region

2. Team Leader/Presentation Webmaster/Documentation
Team Members
Team Leader/Presentation
Ramya Chandrasekaran
Webmaster/Documentation
Pujita Pinnamaneni

3. Project Goal
Design a JAVA Applet to help students understand the characteristics of Schottky diodes.
Demonstrate the energy band gap and depletion width variations for varying concentrations and for different metals and semiconductors.
Demonstrate how the free carrier concentration varies with temperature.

4. Project Outline Review semiconductor physics of Schottky diodes.
Develop simulation for band gap variation with respect to concentration for different metals and semiconductors.
Develop simulation of n/ND and p/NA vs.temperature.

5. Project Outline(cont.)
Develop JAVA code to run these simulations.
Design JAVA applets.
Demonstrate the applets.
Launch the Applets on the World Wide Web.

6. Importance of JAVA Applets
JAVA enables to develop user friendly applications.
JAVA is the web language.
Enables easy interaction .
GUI concepts in JAVA accepts user inputs through mouse and keyboard and enables immediate feedback.
Animations and interactive applications are possible.

7. Importance of Schottky diodes
The role of schottky diodes is firmly established in the semiconductor technology because they perform functions better than most of the other junction devices.
These contacts are used in large number of devices such as FETs,BJTs,photo detectors,LEDs,Double Heterostructure lasers and Solar cells.
Metal - Semiconductor junction are used for high speed rectification.

8. Simulation of Schottky diodes.
Schottky diodes are formed in two ways:
Metals deposited on n-type semiconductor.
Metals deposited on p-type semiconductor.

9. Schottky Contacts.
In n-type Schottky contacts,electrons flow from the conduction band states in the semiconductor to the metal because they have higher energy states.
In p-type Schottky contacts,electrons flow from the metal to semiconductor.

10. Metal on n-type Semiconductor

11. Metal on p-type Semiconductor.

12. Temperature Vs Free carrier Concentration
The regions on the curve are:
Freeze-out:
Depicts the unionized dopants
Extrinsic Region:
Represents ionized dopants and control conductivity.
Intrinsic Region:
Characterizes broken covalent bonds

13. Basic Principles(cont…)

14. Physics Involved The intrinsic carrier concentration is calculated
ni = nio * (T/To)1.5 * exp [(Eg / 2KTo) * (1- To/T)
ND1= [( Nd1/ (1+2[Nd1/(NCO * ni1.5)] ) exp (( Ec – Ed1)/KT)]
ni : Intrinsic Carrier Concentration.
nio :Intrinsic Carrier Concentration at equilibrium.
Eg : Band Gap Energy.
K : Boltzman Constant = * 10-5.
To : Temperature at Equilibrium 300 K.
T : Temperature.
NCO : Density of state at equilibrium in the conduction band.
Ec : Energy level of the Conduction band.
Nd1 : Carrier Density.

15. Conclusions
Simulation of Schottky diodes using JAVA Applets is accomplished.
Temperature Vs. Free carrier concentration curves for different semiconductors have been plotted.
Applets have been successfully hosted on the World wide web.