Other diode technologies

Chapter 3.13 Other diode technologies

Lessons In Electric Circuits Volume III – Semiconductors Book
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Lessons In Electric Circuits Volume III – Semiconductors Book

  • 3.13. OTHER DIODE TECHNOLOGIES163or laser diode’s optimum forward current. This is especially important for the laser diode, notso much for the LED, as regular LEDs tend to be more tolerant of forward current variations.Another application is in the charging of small secondary-cell batteries, where a constantcharging current leads to predictable charging times. Of course, large secondary-cell batterybanks might also benefit from constant-current charging, but constant-current diodes tend tobe very small devices, limited to regulating currents in the milliamp range.3.13Other diode technologies3.13.1SiC diodesDiodes manufactured from silicon carbide are capable of high temperature operation to 400oC.This could be in a high temperature environment: down hole oil well logging, gas turbineengines, auto engines. Or, operation in a moderate environment at high power dissipation.Nuclear and space applications are promising as SiC is 100 times more resistant to radiationcompared with silicon. SiC is a better conductor of heat than any metal. Thus, SiC is betterthan silicon at conducting away heat. Breakdown voltage is several kV. SiC power devices areexpected to reduce electrical energy losses in the power industry by a factor of 100.3.13.2Polymer diodeDiodes based on organic chemicals have been produced using low temperature processes. Holerich and electron rich conductive polymers may be ink jet printed in layers. Most of the re-search and development is of the organic LED(OLED). However, development of inexpensiveprintable organic RFID (radio frequency identification) tags is on going. In this effort, a pen-tacene organic rectifier has been operated at 50 MHz. Rectification to 800 MHz is a develop-ment goal. An inexpensive metal insulator metal(MIM) diode acting like a back-to-back zenerdiode clipper has been delveloped. Also, a tunnel diode like device has been fabricated.3.14SPICE modelsThe SPICE circuit simulation program provides for modeling diodes in circuit simulations.The diode model is based on characterization of individual devices as described in a productdata sheet and manufacturing process characteristics not listed. Some information has beenextracted from a 1N4004 data sheet in Figure 173,3.86.The diode statement begins with a diode element name which must begin with “d” plusoptional characters. Example diode element names include: d1, d2, dtest, da, db, d101. Twonode numbers specify the connection of the anode and cathode, respectively, to other compo-nents. The node numbers are followed by a model name, referring to a subsequent “.model”statement.The model statement line begins with “.model,” followed by the model name matchingone or more diode statements. Next, a “d” indicates a diode is being modeled. The remain-der of the model statement is a list of optional diode parameters of the form Parameter-