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JAVA Applets for Physical Electronics. Metal Semiconductor Metal Semiconductor Depletion Region Team Members Team Leader/Presentation Ramya Chandrasekaran Webmaster/Documentation Pujita Pinnamaneni 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. 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. Project Outline(cont.) • Develop JAVA code to run these simulations. • Design JAVA applets. • Demonstrate the applets. • Launch the Applets on the World Wide Web. 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. 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. Simulation of Schottky diodes. Schottky diodes are formed in two ways: • Metals deposited on n-type semiconductor. • Metals deposited on p-type semiconductor. 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. Metal on n-type Semiconductor Metal on p-type Semiconductor. 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 Basic Principles(cont…) 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)] 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.