Effects of Temperature

• in case of forward bias region the characteristics of silicon diode shift at the rate of 2.5 millivolts per degree centigrade rise in temperature
• for reverse bias condition, the reverse saturated current doubles for every 10 degree centigrade rise in temperature
• reverse saturated current increase with increase in temperature
• for high temperature applications, reverse saturation current should be closer to 10 picoampere
• reverse saturation current for germanium is high
• silicon, gallium arsenide saturation current is smaller
• the application of germanium is limited because of high reverse saturation current. and silicon and gallium arsenide have relatively smaller saturation current at room temperature
• The reverse saturation current Is will just about double in magnitude for every 10°C increase in temperature
• • Reverse-Bias Region: When a diode is in reverse-bias, it should ideally block current from flowing. However, a small leakage current can still flow.
• • Leakage Current is the small amount of current that flows when the diode is in reverse-bias.
• • Germanium diodes have higher leakage currents compared to silicon diodes.
• • As temperature increases, the leakage current in a diode also increases.
• • For a germanium diode, this increase can be significant. For example, at room temperature (25°C), it might have a leakage current of 1 or 2 microamperes (µA), but at 100°C, this can rise to 100 microamperes (µA) or 0.1 milliamperes (mA). This means it leaks more current as it gets hotter.
• • Silicon diodes, on the other hand, have much lower leakage currents even at higher temperatures. This is one reason why silicon is preferred over germanium in many electronic designs.
• threshold voltage

  • The threshold voltage (the minimum voltage needed for a diode to start conducting in the forward direction) also drops as temperature rises.
  • This means that at higher temperatures, the diode starts conducting at a lower voltage.
• • Because silicon diodes have lower leakage currents and maintain better performance at high temperatures, they are more widely used in electronic circuits compared to germanium diodes.
• • Higher temperatures make diodes behave more ideally in the forward direction but can have negative effects on their maximum power and current handling capabilities.