We are Apogeeweb Semiconductor Electronic

WELCOME TO OUR BLOG

Home arrow Diodes arrow Si Diode vs Ge Diode: Parameters and Uses Comparison

arrow left

arrow right

Si Diode vs Ge Diode: Parameters and Uses Comparison

Author: Apogeeweb
Date: 28 Jul 2021
 1126
germanium diode voltage drop

Introduction

In electronics, the diode has the unique characteristic of unidirectional conduction. The main functions are rectification, voltage stabilization, and detection. In addition, there are light-emitting diodes(LED) added with different materials for indication and illumination. In a diode circuit, current can only flow in from the anode and flow out of the cathode. According to different circuit requirements, there are many different types of diodes to choose from. Most of the early diodes were made of germanium single crystals. Later, with the solution of silicon materials and manufacturing processes, silicon tubes have been developed and popularized. Here's how to distinguish silicon(Si) diodes and germanium(Ge) diodes.

Catalog

Introduction

Ⅰ Circuit Properties: Si Tube vs Ge Tube

1.1 Differences between Ge and Si Diode

1.2 Differences between Ge and Si Transistor

1.3 Summery

Ⅱ Common Diode Types Uses

Ⅲ Common Transistor Models Uses

Ⅳ New Development: SiC Schottky Diodes

4.1 SiC Schottky Diode Basic

4.2 SiC Tech Characteristics

4.3 SiC Schottky Diode Applications


Ⅰ Circuit Properties: Si Tube vs Ge Tube

1.1 Differences between Ge and Si Diode

germanium diode silicon diode

The circuit properties of Si diodes and Ge diodes are the same, and the manufacturing process is also the same. Due to the difference in materials, the thermal stability of Si diodes is good, and the thermal stability of Ge diodes is slightly poor.
1) When the current is the same, the DC resistance of the Ge tube is smaller than that of the Si tube. However, as for AC resistance, the situation is opposite.
2) According to experimental research, the Ge diode starts to have current at 0.2V in the forward direction, while the Si diode does not start to have current until 0.5V, that is to say, the initial voltages for the two to reach conduction are different.
3) Under reverse voltage, the leakage current of silicon tube is much smaller than that of germanium tube. After the start of conduction, the Ge tube current increases slowly, and the Si tube current increases relatively quickly.
4) The threshold voltage of silicon tube is higher than that of germanium tube, because the threshold current of silicon tube is much smaller than that of germanium tube. Generally, the threshold voltage of a silicon tube is about 0.5V~0.6V, and the threshold voltage of a germanium tube is about 0.1V~0.2V.
5) Temperature changes have a greater impact on Ge diodes, but less on silicon diodes. Therefore, silicon tubes have better high temperature resistance than Ge tubes.
6) Forward voltage required for diode conduction:

Diode Types

Forward Conduction Voltage

Si

0.7V

Ge

0.15V


It can be seen from the above table that the forward voltage required for the silicon tube to be turned on is higher than that of the germanium tube, so the diode can be distinguished by knowing the forward voltage.
In addition, there is a very direct method to measure your diode with the Ω barrier of a multimeter. As shown in the figure, the red pen (anode) of the multimeter is connected to the cathode of the diode, and the black pen (cathode) is connected to the anode of the diode. If the resistance of the tested diode is around 1kΩ, it is a germanium tube; if the resistance is 4~8kΩ, it is a silicon tube.

si and ge diode test


Compared with germanium diodes, silicon diodes have higher voltage resistance, shorter response time, and stable performance. In most circuits, silicon tubes can replace germanium tubes, but its forward pressure drop is higher than that of germanium tubes. Therefore, in some specific environments, such as small signal detection circuits, germanium tubes are better.

germanium element silion element

1.2 Differences between Ge and Si Transistor

The main difference is that the junction voltage drop is different, the forward voltage drop of the germanium tube is lower about 0.3V, and the silicon tube is higher about 0.7V. In addition, silicon materials are abundant and manufacturing processes are suitable for mass production, so they are widely used and become the protagonist of electronic devices.
Germanium semiconductor materials have high electron mobility and are suitable for low-voltage and high-current devices, but the temperature characteristics of it is worse than that of silicon materials. The reverse leakage current of PN junctions is much larger than that of silicon materials. Therefore, silicon tubes have to be used in high-power devices and high back-pressure devices. 
The triode has two PN junctions. In terms of a PN junction, the forward voltage of the PN junction of the germanium tube is reduced to only 0.3V, while the silicon tube is 0.7V. The reverse withstand voltage germanium tube is very low, so it is easy to reverse breakdown. Therefore, the penetrating current of the Ge tube is relatively large, noise will be generated in the amplifying circuit, and it is easy to be damaged. 

1.3 Summery

Germanium diodes was used a lot in early electronics, such as radios, but they have largely been replaced by silicon diodes. Because the structure of germanium crystals will be destroyed at higher temperature, while Silicon crystals are not easily damaged by excess heat. What's more, peak inverse voltage ratings of silicon diodes are greater than germanium diodes. As for price, Silicon material has low cost and its producibility of high quality silicon dioxide needed for impurity diffusion and surface passivation processes. Therefore, germanium tubes were only produced before the 1970s.

 

Ⅱ Common Diode Types Uses

① Zener Diodes
The Zener diode is also made of a PN structure. It is in the reverse breakdown state when working (the ordinary diode will be damaged in the reverse breakdown zone). When connected to the circuit, it should be reversed, that is, the anode of the Zener diode should be connected with the cathode of the voltage stabilizing circuit, so is the rest. The voltage stabilizing tube uses its reverse breakdown current to change in a wide range, the reverse breakdown voltage is basically unchanged, to achieve the purpose of voltage stabilization.
② Light-emitting Diodes
The light-emitting diode emits light when it passes forward current, and has the performance of electro-optical conversion. The visible light includes red, yellow, green, blue, purple, etc. It is widely used in various electronic equipment as working status indicator.
③ Photodiodes
The reverse current of the photodiode increases with the increase of the light intensity. Its main feature is: the tube works in the reverse state, and the reverse current is proportional to the illuminance.
Rectifier Diodes for Automobiles
The working principle of the diode for automobile silicon rectifier generator is basically the same as that of other diodes, but the external structure is different from that of general diodes. It has one lead pole and the other pole is a shell. It is divided into two types: positive diode and negative diode. The terminal is the positive pole and the shell is the negative pole, while the leading end of the negative diode is the negative pole and the shell is the positive pole. In order to facilitate identification, the positive diode is usually coated with a red dot and the negative diode is coated with a black dot.
⑤ Freewheeling Diode
Freewheeling diodes are common used in automobiles. In addition, fast recovery diode (a kind of semiconductor diode with good switching characteristics and short reverse recovery time) is mainly used for switching power devices (such as IGBT or MOSFET) of various power converters to play a freewheeling effect.

 

Ⅲ Common Transistor Models Uses

The following table lists some commonly used transistor models and their main parameters, packages and alternative models.

Model

Basic Parameters

Description

Pc

VCBO

VCEO

VEBO

hFE

IC

2SC2655

(NPN, TO-92L)

0.9W

50V

50V

5V

*

2A

High-speed switching tube, used for high-current PWM push-pull drive, complementary to the 2SA1020

2SC9013

(NPN, TO-92)

0.625W

40V

20V

5V

84-202

0.5A

Complementary to  the SS9012

2N5551

(NPN, TO-92)

0.63W

180V

160V

6V

30-250

0.3A

High voltage tube, complementary to the 2N5401

KSP2222A(PN2222A)

(NPN, TO-92)

0.625W

75V

40V

6V

35-300

06A

Universal switch type, complementary to the KSP2907A

S8050

(NPN, TO-92)

0.625W

40V

25V

5V

50-300

0.5A

Complementary to the S8550

BD681A

(NPN, TO-126

40W

100V

100V

5V

750-1500

4A

Can drive large relays, Darlington tube

TIP41/A/B/C

(NPN, TO-220)

60W

40~100V

40~100V

5V

15-75

6A

Middle Power tubes, complementary to the TIP42, can be used for IGBT PWM drive

MPSA44

(NPN, TO-92)

0.625W

500V

400V

6V

40-300

0.3A

High voltage tube

KSP2907A

(PNP, TO-92)

0.625W

-60V

-60V

-5V

50-300

0.6A

Common-type, complementary to the KSP2222A

S8550

(PNP, TO-92)

0.625W

-40V

-25V

-5V

50-300

0.5A

Complementary to the S8050

2SA1020

(PNP, TO-92L)

0.9W

-50V

-50V

-5V

40-240

2A

High-speed switch tube, complementary to the 2SC2655

2SA684

(PNP, TO-92L)

1W

-60V

-50V

-5V

50-340

1A

Darlington tube

TIP42/A/B/C

(PNP, TO-220)

65W

-40~-100V

-40~-100V

-5V

15-75

6A

Middle power tubes, complementary to the TIP41, can be used for IGBT PWM drive

KSP94

(PNP, TO-92)

0.625W

-400V

-400V

-6V

40-300

0.3A

High voltage tube


Ⅳ New Development: SiC Schottky Diodes

4.1 SiC Schottky Diode Basic

Schottky diodes, also known as hot carrier diodes, form a Schottky barrier through metal and semiconductor contacts to achieve rectification. Compared with ordinary PN junction diodes, the reverse recovery inertia of it is very low. Therefore, Schottky diodes are suitable for high-frequency rectification or high-speed switching.
Silicon carbide (SiC) is a high-performance semiconductor material, so SiC Schottky diode have advantages of higher energy efficiency, higher power density, smaller size and higher reliability. It can be used in power electronics to break the limit of silicon, and becomes the preferred device for new energy and power electronics.

4.2 SiC Tech Characteristics

SiC is a compound semiconductor composed of silicon and carbide. It provides a number of advantages over silicon. The band gap of SiC is 2.8 times that of silicon (wide band gap), reaching 3.09 eV. Its insulation breakdown field strength is 5.3 times that of silicon, up to 3.2MV/cm, and its thermal conductivity is 3.3 times that of silicon, about 49w/cm·k. Like silicon semiconductor materials, it can be made into junction devices, field-effect devices, and special Schottky diodes. Here is SiC characteristics:

silicon carbide

1) Silicon carbide single-carrier devices have a thin drift region and low on-state resistance, about 100-300 times smaller than silicon devices. Due to the small on-resistance, the forward loss of the silicon carbide power device is small.
2) The silicon carbide power device has a high breakdown voltage due to its high breakdown electric field. For example, the voltage of commercial silicon Schottky diode is less than 300V, while the breakdown voltage of the first commercial SiC Schottky diode has reached 600V.
3) SiC has higher thermal conductivity.
4) SiC devices can work at higher temperatures, while the maximum operating temperature of Si devices is only at 150ºC.
5) SiC has high resistance to radiation.
6) The forward and reverse characteristics of SiC power devices vary little with temperature and time, and their reliability is good.
7) SiC devices have good reverse recovery characteristics, with low reverse recovery current and switching loss.
8) SiC devices can reduce the volume of power devices and circuit losses.

4.3 SiC Schottky Diode Applications

SiC Schottky diodes can be widely used in medium and high power fields such as switching power supplies, power factor correction (PFC) circuits, uninterruptible power supplies (UPS), photovoltaic inverters, etc., which can significantly reduce circuit losses and improve circuit operating frequency.
Substituting SiC SBD(Schottky barrier diodes) for the original silicon FRD(fast recovery diodes) in the PFC circuit can make the circuit work above 300kHz, and the efficiency remains basically unchanged, while the efficiency of the circuit using silicon FRD above 100kHz drops sharply. As the operating frequency increases, the volume of passive components such as inductors decreases correspondingly, and the volume of the entire circuit board decreases by more than 30%.

 

Frequently Asked Questions about Silicon and Germanium Diodes

1. Why silicon diode is better than germanium diode?
The structure of Germanium crystals will be destroyed at higher temperature. However, Silicon crystals are not easily damaged by excess heat. Peak Inverse Voltage ratings of Silicon diodes are greater than Germanium diodes. Si is less expensive due to the greater abundance of element.

 

2. How can I tell if I have a Ge or Si diode?
You can easily distinguish Silicon and Germanium Diodes. Silicon diodes should read approx 0.7V and Germanium diodes should read 0.3V. A little difficult to distinguish Schottky diodes though. They should show approx 0.2V which is close to 0.3V.

 

3. What are the differences between silicon and germanium semiconductor?
The key difference between silicon and germanium is that the Germanium has d electrons, but Silicon does not have any d electrons. Silicon and germanium, are both in the same group (group 14) of the periodic table. Hence, they have four electrons in the outer energy level.

 

4. What is difference between silicon and germanium?
Silicon and germanium have four valence electrons but at the given temperature germanium will have more free electrons and higher conductivity than silicon. Silicon is more widely used in the electronic device than germanium since it can be used at a higher temperature.

 

5. What is the difference between silicon and germanium transistors?
To answer you actual question, there are two significant differences between silicon and germanium transistors: germanium has a low melting point and germanium transistors have much less tolerance for high temperatures. The forward voltage drop of a germanium junction is lower than for silicon.

Best Sales of diode

Photo Part Company Description Pricing (USD)
A3918SESTR-T A3918SESTR-T Company:Allegro MicroSystems Remark:IC MOTOR DRIVER 2.5V-9V 16QFN Price:
1500+: $0.64400
Inquiry
AM29F800BB-120EC AM29F800BB-120EC Company:AMD Remark:Flash, 512KX16, 120ns, PDSO48, MO-142DD, TSOP-48 Price:
Call
Inquiry
MDT420M03001 MDT420M03001 Company:Amphenol ICC (FCI) Remark:67 Position Female Connector Gold 0.020" (0.50mm) Black Price:
1+: $1.64000
10+: $1.48700
25+: $1.39640
50+: $1.33560
100+: $1.27490
250+: $1.15348
800+: $1.03208
1600+: $0.88029
2400+: $0.84994
5600+: $0.80744
8000+: $0.78923
Inquiry
AD9640ABCPZ-150 AD9640ABCPZ-150 Company:Analog Devices Inc. Remark:IC ADC 14BIT PIPELINED 64LFCSP Price:
1+: $150.83000
Inquiry
ADSP-21488BSWZ-4B ADSP-21488BSWZ-4B Company:Analog Devices Inc. Remark:IC CCD SIGNAL PROCESSOR 176LQFP Price:
1+: $28.41000
10+: $26.20200
25+: $25.02400
100+: $21.34400
Inquiry
AD5554BRSZ AD5554BRSZ Company:Analog Devices Inc. Remark:IC DAC 14BIT A-OUT 28SSOP Price:
1+: $33.22000
10+: $30.63400
25+: $29.25720
100+: $24.95450
Inquiry

Alternative Models

Part Compare Manufacturers Category Description
Mfr.Part#:TLV1572IDR Compare: TLV1572ID VS TLV1572IDR Manufacturers:TI Category:Analog to Digital Description: 10Bit, 1.25MSPS ADC Single Ch., DSP/(Q)SPI IF, S&H, Very Low Power, Auto PowerDown 8-SOIC -40℃ to 85℃
Mfr.Part#:TLV320AIC23BIPWR Compare: Current Part Manufacturers:TI Category:CODECs Description: Stereo Audio Interface 16B, 20B, 24B, 32B I2C 28-TSSOP
Mfr.Part#:TLV320AIC23BIPW Compare: TLV320AIC23BIPWR VS TLV320AIC23BIPW Manufacturers:TI Category:CODECs Description: Audio Codec 2ADC / 2DAC 32Bit 28Pin TSSOP Tube
Mfr.Part#:TLV320AIC23BIPWRQ1 Compare: TLV320AIC23BIPWR VS TLV320AIC23BIPWRQ1 Manufacturers:TI Category:CODECs Description: Audio Codec 2ADC / 2DAC 32Bit 28Pin TSSOP T/R

Ordering & Quality

Image Mfr. Part # Company Description Package PDF Qty Pricing (USD)
AD629ARZ-R7 AD629ARZ-R7 Company:Analog Devices Inc. Remark:IC OPAMP DIFF 1 CIRCUIT 8SOIC Package:8-SOIC (0.154", 3.90mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
1000+: $4.74150
Inquiry
AD736KNZ AD736KNZ Company:Analog Devices Inc. Remark:IC RMS TO DC CONVERTER 8DIP Package:8-DIP (0.300", 7.62mm)
DataSheet
In Stock:96
Inquiry
Price:
Call
Inquiry
AD7606BSTZ-4 AD7606BSTZ-4 Company:Analog Devices Inc. Remark:IC DAS/ADC 16BIT 200K 64LQFP Package:64-LQFP
DataSheet
In Stock:298
Inquiry
Price:
1+: $21.11000
10+: $19.47300
25+: $18.59800
100+: $15.86300
Inquiry
AD7791BRMZ-REEL AD7791BRMZ-REEL Company:Analog Devices Inc. Remark:IC ADC 24BIT SIGMA-DELTA 10MSOP Package:10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
3000+: $5.91600
Inquiry
AD8529ARZ AD8529ARZ Company:Analog Devices Inc. Remark:IC OPAMP GP 2 CIRCUIT 8SOIC Package:8-SOIC (0.154", 3.90mm Width)
DataSheet
In Stock:219
Inquiry
Price:
1+: $3.21000
10+: $2.88000
25+: $2.72240
100+: $2.23850
250+: $2.00860
500+: $1.93600
1000+: $1.75450
Inquiry
AD9983AKCPZ-170 AD9983AKCPZ-170 Company:Analog Devices Inc. Remark:IC INTERFACE SPECIALIZED 64LFCSP Package:64-VFQFN Exposed Pad, CSP
DataSheet
In Stock:170
Inquiry
Price:
1+: $12.35000
10+: $11.34800
25+: $10.87800
100+: $9.11400
250+: $8.52600
Inquiry
ADF4206BRUZ-RL ADF4206BRUZ-RL Company:Analog Devices Inc. Remark:IC PLL FREQ SYNTHESIZER 16TSSOP Package:16-TSSOP (0.173", 4.40mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
Call
Inquiry
ADG1612BCPZ-REEL7 ADG1612BCPZ-REEL7 Company:Analog Devices Inc. Remark:IC SWITCH QUAD SPST 16LFCSP Package:16-VQFN Exposed Pad, CSP
DataSheet
In Stock:On Order
Inquiry
Price:
1500+: $2.61000
Inquiry

Related Articles

pinglun 0 comment

Leave a Reply

Your email address will not be published.

 
 
   
 
code image
Rating: poor fair good very good excellent

# 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z