Semiconductor devices are nothing but electronic parts that use semiconductor materials to allow the passage of electric current to pass through them. Semiconductor materials usually comprise gallium arsenide, germanium, or silicon and are typically used as light emitters, rectifiers, oscillators, and other equipment.
After their introduction in the early 1950s, semiconductors became the key material in producing electronics and their variants like thermoelectrics. Today, they are preferred over vacuum tubes in a large range of applications. Compared to using thermionic emission in high vacuums, semiconductor devices rely on electronic conduction in the solid-state for their function.
Diodes Are the Most Popular Type of Semiconductor Devices
Have you ever heard of diodes? These are “two-terminal” semiconductor devices that enable electric current to pass in one direction while inhibiting its flow in the reverse direction. A diode consists of two materials called P and N. Joining p-type and n-type materials results in the creation of P-n functions. Since the p-type region has a greater number of hole concentrations while the n-type region has a higher number of electron concentrations, the electrons get diffused from the latter to the former’s region. Diodes designed to make use of this phenomenon are referred to as photodiodes.
Manufacturers can use diodes for various purposing, including a signal’s simple rectification, as power diodes for signal detection, power rectification, light generation, laser light generation, and more. The semiconductor device also comes in a range of different packages: standard wire diodes, surface mount diodes, and power diodes can even be bolted to heatsinks.
In PCB assembly, you’ll find a whole raft of diodes such as SMD diodes (surface mounted diodes), as much of the board assembly nowadays relies on surface mount assembly technology. SMD diodes have several standard packages, including the “SOT-23” package that’s used for small, discrete diodes. Due to SMD diodes’ tiny size, the manufacturer doesn’t have enough room to place the full part-number on the semiconductor. This is why most assemblies have to rely on short-form numbers to distinguish them from each other.
Other Semiconductor Devices You Should Know About
Although diodes are the most discussed semiconductors in the electronics industry, various other semiconductor devices also have important functions. Here are some interesting ones:
Transistors come in the following types:
- Bipolar junction transistor
- Field-effect transistor
Here’s a look at each transistor:
- Bipolar junction transistor
The first transistor is composed of 2 PN structures (a collector junction and a transmitting junction). A thin layer of semiconductor material – called base region – is present between the two junctions. A base electrode is also connected to the base region. Application-wise, the collector junction is reverse biased while the transmission junction is forward biased. The current at the emitting junction causes a wide range of minority carriers to be injected into the base region, diffusing the collector junction to create a collector current. Only a small portion of these carriers meet again in the base region. The collector current to the base current ratio is known as “the common-emitter current amplification factor.”
A bipolar transistor’s current amplification effect comes through the common-emitter circuit, where a slight change in the base current can significantly influence the collector current. Bipolar junction transistors can be categorized into two types: p-n-p or n-p-n.
- Field-effect transistor
The field-effect transistor functions based on the semiconductor activity decreasing or increasing by an electric field’s presence. The field can multiply the number of holes and electrons present in the conductor, thereby modifying its conductivity. A reverse-biased p-n junction can accommodate the electric field, forming a JFET (junction field-effect transistor). A MOSFET (metal-oxide semiconductor field-effect transistor) can also be formed by an oxide layer insulating an electrode from the bulk material.
Currently, MOSFET transistors are the most widely used, especially in the production of large-scale integrated circuits. MOS devices ensure a CCD (charge-coupled device) is developed by leveraging the charge near the semiconductor’s surface as information. The process also involves controlling the well near the surface to transmit the charge in a specific direction. You can use these devices as a memory and a delay line, etc. You can also use them with a photodiode array as a video tube.
That said, all transistors can serve as the building block of logic gates, which play a significant role in digital circuits’ design. The transistors could act as an on-off switch in digital circuits like microprocessors. For instance, the voltage in MOSFET is applied to the gate to determine whether the switch is active or inactive.
These are analog circuit blocks that PCB assemblers use to produce high-performance circuits (with minimal components). Capacitors, filters, amplifiers, and the likes can use these circuits by leveraging a positive or negative feedback system. These are “liners” containing properties like the ones in DC amplifiers. Operation amplifiers have three critical terminals: non-inverting input, inverting input, and the output terminal. Each of these can be either source or sink voltage and current.
Operational amplifiers have a range of applications. For example, you can use them to compare signals, where the amplifiers help to compare the voltage applied at one to the other input end. They can also be used for buffer signals; high input impedance allows the amplifier to avoid high current gain and signal slow loading issues. Moreover, manufacturers can use these amplifiers to amplify signal input depending on the voltage in its inverting and non-inverting input terminals.
There you have it – the different types of semiconductor devices used in the electronics manufacturing industry. The devices mentioned above comprise two-terminal and three-terminal devices. There are also four-terminal devices like the hall effect sensor and photo coupler, but they aren’t as popular as the other two. Most semiconductor devices do not have any filaments, so no power is required to heat them to generate electrons’ emission. And because of the no heating requirement, the devices switch into operation as soon as the circuit turns on. Compared to vacuum tubes, these devices are cheaper and require a low voltage to operate.