The key difference between silicon diode and germanium diode is that a silicon diode has a high forward voltage and high-temperature stability than a germanium diode.
A silicon diode is a semiconductor having a positive and negative charge polarity, which allows the electrical current to flow in one direction, whereas a germanium diode is a diode made using the element germanium instead of silicon. Both silicon and germanium are useful in making diodes. But these two are different from each other in some aspects.
CONTENTS
1. Overview and Key Difference
2. What is Silicon Diode
3. What is Germanium Diode
4. Silicon Diode vs Germanium Diode in Tabular Form
5. Summary – Silicon Diode vs Germanium Diode
What is Silicon Diode?
A silicon diode is a semiconductor having a positive and negative polarity, which allows electrical current to flow in a single direction while restricting movement in another direction. Usually, the threshold voltage of a silicon diode is 0.7V. It has a high-temperature stability of about 200 degrees Celsius. Moreover, the leakage current of this diode is in nA, and peak inverse voltage (PIV) is high for the silicon diode. PIV is the maximum voltage the diode can withstand before the breakdown in the reverse-biased direction.
Furthermore, silicon diodes can work maximally up to 170 degrees Celsius, and the reverse bias saturation current is very high. These diodes are preferred as rectifiers. The forward break-over voltage of the silicon diode is very high, and it loses about 0.7 – 0.9 V. The silicon crystals have the capacity to withstand high temperatures and are comparatively cheaper as well. Moreover, the forward voltage drop for silicon diode junction is low.
What is Germanium Diode?
A germanium diode is a diode made using the element germanium instead of silicon. The threshold voltage of a silicon diode is 0.3 V. It has low-temperature stability, which is up to 85 degrees Celsius. The leakage current of this diode is in the mA range. The PIV for the germanium diode is low.
Moreover, a germanium diode can work maximally up to 100 degrees Celsius, and the reverse bias saturation current for this diode is high (about 1000 nA). These diodes are useful as lighting sensors. The forward break-over voltage for germanium diodes is low, and it can lose about 0.3 – 0.4 V. Further, germanium diodes cannot withstand very high temperatures comparatively, and these are expensive as well. The forward voltage drop of the germanium junction is comparatively low.
What is the Difference Between Silicon Diode and Germanium Diode?
A diode is a semiconductor device with two terminals. This allows the flow of current only in one direction. The key difference between silicon diode and germanium diode is that a silicon diode has a high forward voltage than a germanium diode. Moreover, a silicon diode has high-temperature stability (about 200 degrees) Celsius, while a germanium diode has low-temperature stability (about 85 degrees Celsius). Silicon diodes are also cheaper than germanium diodes. In addition, a silicon diode has a threshold voltage of 0.7 V whereas a germanium diode has a threshold voltage of 0.3 V.
The below infographic presents the differences between silicon diode and germanium diode in tabular form for side by side comparison.
Summary – Silicon Diode vs Germanium Diode
A silicon diode is a semiconductor having a positive and negative polarity that can allow electrical current to flow in a single direction while restricting movement in another direction. A germanium diode is a diode made with the use of the element germanium instead of silicon. The key difference between silicon diode and germanium diode is that a silicon diode has a high forward voltage and high-temperature stability than a germanium diode.
Reference:
1. Jessica, Reed “What Is a Germanium Diode?” Easy Tech Junkie, 9 Aug. 2022.
Image Courtesy:
1. “6A8 (6A, 800A max) silicon diode in R-6 axial package (14476119781)” By Mercado Viagens from Brasil – Various Electronic Components (CC BY 2.0) via Commons Wikimedia
2. “Germanium Diode 1N60” By Aomorikuma – Sony Cyber-shot DSC- H3 (CC BY-SA 3.0) via Commons Wikimedia