the valence band energy is different in the two substances,so the cut in voltage is different.
Though germanium diodes were the first ones fabricated, several factors make silicon the choice vs. germanium diodes. Silicon diodes have a greater ease of processing, lower cost, greater power handling, less leakage and more stable temperature characteristics than germanium diodes. Germanium diodes' lower forward drop (.2V to .3V versus .7V to 1.0V) make them better at small signal detection and rectification.
germanium has great intrinsic concentration at room temperature,hence conduction is great in germanum compared to silicon, and resistance decreases in germanum and hence built in potentail also less in germanum compared to silicon.built in potential of silicon is 0.7v built in potential of germanum is 0.3v. 1)intrinsic concentration of germanium at room temperature is 2.5*10^13 atoms/cm^3. 2)intrinsic concentration of silicon at room temperature of 300k is 1.5*10^10 atoms/cm^3.
Germanium has a smaller bandgap compared to silicon, leading to higher intrinsic carrier concentration and hence greater leakage current. Additionally, germanium has a higher intrinsic carrier mobility, which can further contribute to increased leakage current compared to silicon.
Germanium diodes typically have a lower forward voltage drop than silicon diodes, which can result in slightly higher temperatures under the same operating conditions. However, the difference in temperature between the two types of diodes is generally minimal and may vary depending on the specific application.
To forward bias a germanium diode you need to reach between 0.2 and 0.3 V between anode (+) and cathode (-). Once this voltage is reached, the diode will conduct. Make sure you have a resistor to limit the forward current to a safe (for the diode, that is) value.
In semiconductor uses, such as diodes and transistors, the forward voltage drop for Silicon (Si) is a little less than 0.7 volts, while the FVD for Germanium (Ge) is about 0.3 volts.
products made by silicon are more stable than those made by germanium
silicon has a wider bandgap than germenium .silicon jeakage current small, easily available then Ga and break down voltage is more. knee voltage of si is 0.7and Ga is having 0.3then Si is very useful.
Germanium has a smaller band gap compared to silicon, allowing it to conduct electricity more effectively. Its crystal structure also has a closer packing arrangement of atoms compared to silicon, making it more metallic in nature. Overall, these factors contribute to germanium exhibiting more metallic properties than silicon.
The temperature sensitivity of silicon is less than germanium because silicon has a wider energy band gap than germanium. This wider band gap allows silicon to operate more efficiently at higher temperatures, resulting in less temperature-dependent changes in its electrical properties compared to germanium. Additionally, silicon has a higher thermal conductivity than germanium, which helps dissipate heat more effectively, reducing temperature effects on its performance.
silicon diode is preferred more when compared with germanium diode because in silicon diode the operating voltage is 0.7v where as in germanium diode the operating voltage is 0.3v , germanium is temperature sensitive so it can be easily destroyed by increasing temperature hence silicon diode is preferred more
The higher leakage current in germanium compared to silicon is mainly due to its lower bandgap energy, which allows more thermally generated carriers to flow through at room temperature. Additionally, germanium has lower electron mobility and higher intrinsic carrier concentration than silicon, contributing to increased leakage current.
Germanium has four number of shells while Silicon has three number of shell. therefore for germanium less energy is required to move the electron from valence band to conduction band if compared to silicon. So at room temperature for germanium their are more number of electrons present in conduction bond hence more number of holes present in the valence energy band. Due to movement of holes reverse saturation current is produced. Their is more number of hole movement in germanium comparatively therefore reverse saturation current is more than silicon for germanium. You may refer to Electronic Devices and Circuits by Allen Mottershead Regards, Zain Ijaz UCTI, Malaysia Mechatronic Engineer.
Silicon has a higher operating temperature and better thermal stability compared to germanium, making it more reliable for electronic devices. Additionally, silicon's oxide layer forms a better insulating material for integrated circuits, enhancing its performance. Silicon also has a wider bandgap than germanium, allowing for better control of electrical conduction.
If it's a germanium transistor, 0.3 volts. If it's the more common silicon transistor, slightly more than 0.6 volts.
silicon diodes Cut in voltage is 0.7 V.but the Germanium cut in voltage is 0.3 V that's why .............
Germanium diodes are more expensive than silicon ones, germanium is harder to process, germanium cannot be used to make integrated circuits (while early prototype integrated circuits were germanium the wiring between the integrated components cannot be integrated making it too expensive for production), germanium cannot operate with a junction temperature above 60C (silicon will operate up to 150C), and its reverse leakage current is greater. However! Germanium diodes have a lower forward voltage drop than silicon ones do, so they're better for some applications, like radio frequency detection.