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What Are Discrete Semiconductors and How Do They Work?

What Are Discrete Semiconductors and How Do They Work?

November 03 , 2023 0

A world without discrete semiconductors is hard to imagine. In this guide, we'll describe these important components, how they differ from standard semiconductors, and how to use them in a variety of circuit types.

What is a Discrete Semiconductor?

We should first look at three electrical hardware terms: conductor, insulator, and semiconductor, when defining a semiconductor.

Conductor: A conductor is a substance that permits the flow of electrons and, consequently, an electric current when subjected to a voltage. Conductors exhibit low resistance to electrical flow. Some conductors excel in their conductivity, which is why they are commonly employed in electrical wiring. Notable examples of effective conductors are copper and aluminum. Silver and gold exhibit exceptional conductivity, but their use is often restricted due to their status as precious metals. It's worth noting that conductors become less efficient as their temperature rises.
Insulator: An insulator is a material characterized by high resistance to the extent that it can effectively block the flow of electric current. Materials like plastic, rubber, glass, and wood are recognized as good insulators. Plastic, in particular, is widely employed for insulating wiring due to its flexibility and water-resistant properties.
Semiconductor: A semiconductor is a material that falls between proficient conductors and adept insulators. These materials display low resistance under certain conditions and high resistance under others, or they may conduct electricity, although not very efficiently. Semiconductors find utility in circuits where they can perform functions like amplification, switching, or manipulating the electric current. Prominent examples of effective semiconductors include silicon, germanium, and tin. Moreover, when transformed into compounds or alloys, there is a plethora of potential semiconductor materials. It's important to note that semiconductors increase their conductivity as their temperature rises.

Discrete semiconductors are a type of semiconductor, as their name suggests. A semiconductor device that has only one basic function, rather than more complex functions, as with an integrated circuit semiconductor, would be considered a semiconductor device with just one fundamental function.

We will discuss discrete semiconductors in more detail below, including thyristors, Zener diodes, bipolar transistors, bridge rectifiers, and others.

A discrete semiconductor consists of a variety of components, such as transistors, valves, rectifiers, and more. Some are available as modular accessories that can be integrated into existing circuits easily.

The construction of some discrete semiconductors allows them to perform functions similar to those performed by two different devices hooked together in a certain configuration. By providing a circuit with one component, we can save space on a circuit board and access key functionalities that would otherwise require several components.

There are many discrete semiconductor devices that function differently depending on how they are constructed. Thyristors, for example, have four layers of semiconductor material with n- and p-type materials alternately sandwiched together.

Types of Discrete Semiconductors

Discrete semiconductors are individual electronic components that are not integrated into larger circuits or devices. These components serve various functions in electronics and are typically used for specific tasks. Here are some common types of discrete semiconductors:

1.Zener Diodes

The Zener diodes allow electric current to flow in the opposite direction to normal when a certain voltage is reached (the Zener voltage). There are several Zener voltages available, or they can be designed with variable voltages. In a circuit or voltage reference, Zener diodes serve as limiting factors and protection against excess voltage. Electronic devices often use these components for power regulation and circuit overload protection.

2.Thyristors

There are four layers of semiconductor material inside a thyristor, alternating layers of n- and p-type semiconductors, in which it has two stable states. A thyristor has two stable states – it is “bistable”. With a change in current, it remains in that state until it receives another signal. Therefore, it can be used as a switch or a latch. Dimmer switches and power controllers are some of their everyday uses.

3.Varactor Diodes

Varator diodes are also known as variable capacitance diodes, tuning diodes, and Varicap diodes. They are used as capacitors controlled by the voltage applied to them. In transmitters, TV sets, mobile phones, voltage-controlled oscillators, and other devices that transmit or receive FM signals, they are particularly useful. When the voltage is increased or decreased, these devices change their capacitance. Their specific characteristics are determined by the doping profile, and they can only accept AC, not DC.

4.Bipolar Transistor Symbol

In analog circuits, bipolar transistors are often incorporated. As a switch, they allow a large voltage to pass through when a small signal voltage is applied to them. As a result of their carriers utilizing both negative and positive charges, they are referred to as bipolar. In semiconductors, this means that both electrons and holes play a role in their operation. Integrated circuits heavily use bipolar transistors, but they are also sold separately.

5.DIACs

The DIAC is a diode designed to conduct alternate currents. Like the TRIAC above, it operates as a switch and maintains its state until the signal voltage drops below a predetermined holding current. At this point, it reverts to a high resistance state, cutting off the circuit. Power overload protection systems and dimmest switches utilize them.

6.Bridge Rectifiers

A bridge rectifier is constructed out of diodes arranged in a specific configuration - the namesake bridge. As the name implies, this bridge converts alternating current (AC) into direct current (DC), which is a basic function for most electronic devices. Featuring two diode drops and full-wave rectifying, these devices work with two-wire AC input.

7.TRIACs

As a type of thyristor, TRIACs (Triodes for Alternating Current) function as electronic switches, allowing current to flow in either direction when triggered by an input voltage. When triggered by an input voltage, they allow current to flow in both directions. The moment it is switched on, it remains in that state until another trigger switches it off. These devices function similarly to silicone-controlled rectifiers connected in inverse parallel and connected at their gates.

8.Schottky Diodes

A Schottky diode is a semiconductor device that features a junction between a metal and a semiconductor material. Its name originates from the work of the German physicist Walter Schottky, who developed and explored this concept in the 1930s. When employed as a switch, Schottky diodes offer notable advantages, including rapid switching times and a low turn-on voltage. These characteristics make them valuable in a wide range of applications, particularly in radio frequency (RF) applications and as power rectifiers. Additionally, Schottky diodes are instrumental in preventing power discharge from batteries connected to solar panels during periods of reduced sunlight exposure.

9.JFET Transistors

Junction-gate Field-Effect Transistors (JFETs) are a type of field-effect transistor that employs three distinct terminals to regulate the flow of current within an electronic circuit. These three essential terminals are known as the source, drain, and gate. The source and drain terminals serve as the primary conduits for current passage, while the gate terminal acts as the mechanism through which current can be constricted, allowing for either restriction or complete blocking. JFETs are commonly applied in switching applications, although they also have the capability to deliver variable resistance that is contingent upon the voltage applied to them.

10.MOSFET Transistors

Metal Oxide Semiconductor Field-Effect Transistors (MOSFETs) are similar to bipolar transistors in that an input voltage is required. Compared to the larger voltage required by a bipolar transistor, the input voltage for a MOSFET transistor can be tiny.
These are field-effect transistors with four terminals, though most commonly hooked up with three. Two terminals are often short-circuited within the device. In fact, three terminals are commonly used in electrical diagrams, since they include a body, drain, gate, and source terminal. They are the most common transistors.

What Are the Differences Between Discrete Semiconductors and Other Semiconductors?

Numerous semiconductor components are typically marketed as integral parts of circuits, frequently within Integrated Circuits (ICs). These circuits exhibit the capability to perform a variety of distinct functions within a device, setting them apart significantly from discrete semiconductors.

In contrast, a discrete semiconductor has a fundamental function that cannot be subdivided into multiple functions. For instance, an IC may incorporate elements like transistors, diodes, and other components. These individual components can each serve different purposes independently or collaboratively as part of a circuit, collectively accomplishing multiple functions. In contrast, a discrete semiconductor is engineered to perform a singular function. Take a transistor, for example – it inherently functions solely as a transistor.

In today's contemporary landscape, a majority of semiconductors are procured as constituents of integrated circuits. Nevertheless, discrete semiconductors remain an indispensable solution for specific engineering requirements, as they fulfill unique roles within the realm of electronic components.

Given their distinct, discrete nature, certain applications necessitate the acquisition of additional devices to realize the desired functionality in a given circuit. Semiconductor devices contribute to a wide array of functions, ranging from power regulation to acting as switches, among others. For numerous engineering tasks, the availability of discrete semiconductors offers an economically viable avenue for prototyping and production.

Discrete Semiconductors are available at Joinwinchips from industry leading manufacturers. Joinwinchips is an authorized distributor for many discrete semiconductor manufacturers including Infineon, Littelfuse, Nexperia, onsemi, STMicroelectronics, Vishay & more. Please view our large selection of discrete semiconductors.