A transistor is a device that regulates current or voltage flow and acts as a switch or gate for electronic signals. The transistor was invented by three scientists; Shockley, Brattain and Bardeen at the Bell Laboratories in 1947, and has rapidly replaced the vacuum tube as an electronic signal regulator. (Michael, Pentland, Gaut, McKay, & Tacon, 2008)
Modern transistors consist of three layers of a semiconductor material, these ‘solid state devices’ utilise the junction between p-type and a n-type semiconductor to direct the flow of electrons. Electrons close to the p-n junction tend to diffuse from the n-type across the interface and combine with positive holes in the p-type semiconductor, this movement of charge creates a net potential difference across the junction, setting up an electric field that moves from n to p as demonstrated in figure 1 below (Rouse, What is a transistor? – Definition from WhatIs.com, 2015). Consequently, if a voltage is applied to a p-n junction it acts as a diode, allowing current to flow in a single direction.
A microchip is also called an integrated circuit, generally it is a small piece of silicon onto which the transistors making up the microprocessor have been etched. Microchips are made for program logic and for computer memory. Moreover, microchips that include both logic and memory circuitry are designed for special purposes such as analog-to-digital conversion, bit slicing and gateways. (What is a Microchip? – Definition from Techopedia, 2018)
Similarly, a microprocessor, sometimes called a logic chip, is a computer processor on a microchip. The microprocessor contains, the central processing unit (CPU) functions which performs the instructions and tasks involved in computer processing (Bernstien, 2000). In a computer system, the microprocessor is designed to perform arithmetic and logic operations that make use of small number-holding areas called registers. Based on the instructions, a microprocessor does three basic things: using its ALU (arithmetic/logic unit), a microprocessor can perform mathematical operations like addition, subtraction, multiplication and division, a microprocessor can move data from one memory location to another and a microprocessor can make decisions and jump to a new set of instructions based on those decisions (Brain, 2018). Microprocessors have two distinctive functions based on these three available operations, the first being RAM (random access memory) which allows the processor to store random bits of information, the second being ROM (read only memory) which is programmed with a permanent collection of pre-set bytes. (Rouse, 2006)
Microchips and microprocessors have brought society into the modern era as they have enabled the mobility of mobile phones and computers, however, without the invention of the transistor, both technologies would be unable to operate.
Transistors are used in computers through the operation of integrated circuits, an integrated circuit is a complete circuit that is simplified and compacted onto the surface of a piece of silicon. For a current to flow within a transistor, a voltage must be applied to the gate which sits above the p-n junction. The transistor then forms a logic gate that transmits 1s and 0s through the microprocessor (Bernstein, 2000). This allows integrated circuits to transform electrical current into usable data which effectively allows the communication of complex information and tasks through the computer in the form of binary code. (Chandler, 2018)
But how is this used in microchips and microprocessors? The role of the microchip is to store information, consequently transistors play the role of controlling the information that is used and how the chip operates. Similarly, because microprocessors do not have sufficient enough memory to store program instructions and data, separate integrated circuits, RAM chips, which contain a large number of transistors are used in conjunction with the microprocessor to provide the needed memory (Woodford, 2018).
The function of transistors in microchips and microprocessors has allowed for major advancements in technologies. The miniscule size of the transistor has contributed to the practicality of this device, with much lower voltage requirements, significantly less heat produced and a considerably smaller design to thermionic devices (vacuum tubes) (Michael, Pentland, Gaut, McKay, & Tacon, 2008). Transistors work primarily as switches and amplifiers, given these functions one of the earliest uses of transistors on a large scale is in hearing aids. Before transistors electrical hearing aids operated using vacuum tubes which were able to increase sound levels by as much as 70 dB (Packer, 2016), however because of the size of vacuum tubes, these hearing aids were very large causing inconvenience to the consumer. A specific example of this is in the Philips KL 5500 hearing aid, which uses four transistors to amplify the supply voltage of 1.5V to an output of 1 mW, which has been seen as quite sufficient in extreme cases of deafness. (Blom, 1957)
Additionally, transistor radios have been developed to be used in place of thermionic devices. Soundwaves are received and recorded through a microphone and turned into electrical signals. These signals travel through a circuit, and the transistor amplifies the signal, which is subsequently much louder when it reaches the speaker (Chandler N. , 2001). Using this application of transistors Texas Instruments were able to develop small, pocket-sized transistor radios called the Regency TR-1, which was announced on Oct. 18, 1954.
Since the invention of the transistor in 1947, computing capacity has increased exponentially, resulting in significant improvements in the tools and knowledge we have in the community of health care professionals (Maris, 2015). Currently, we are experiencing a transistor movement for the human body, as health care begins to improve at the same exponential pace as technology, resulting in the merging of computing and medicine. This is specifically evident with the application of transistors in implants, where biologically adaptive, flexible transistors have been created to help doctors learn more about what is happening inside a patient’s body and stimulate body treatments (Ladson, 2014). This is one of the first demonstrations of transistors that can change shape and maintain their electrical properties after being implanted in the body, creating a device that is compatible with human tissue. Effectively revolutionising the health industry.
To summarize, through the development and application of transistors there have been major improvements in the way we communicate, store information and perform certain tasks. Technologies have seen major improvements in cost, convenience and application, which is evident in both the development of the transistor hearing aid and transistor radios as described above. Additionally, the application of transistors with the global health care industry has led to major breakthroughs in the way we now perform certain surgeries, which is evident in the development of transistor implants as described above. Ultimately, through their application in electronics, transistors have improved the communal quality of life of individuals throughout the global community, demonstrating how transistors have had a predominantly positive impact on society.