FAST, PRESENT AND FUTURE OF ELECTRONICS DEVICES IN NANO REGIME
- Vacuum Tube Era:
Electronics comes under the branch of physics and technology concerned with designing circuits using transistors, microchips etc. It is the behavior and movement of electrons in a semiconductor, conductor, vacuum or gas. It is tough to forecast where the electronics is started. Our daily life becomes more accessible and comfortable with the help of these electronic applications. Our electronic world is not just the effort; and it is the hard work of the great minds. Electronics is the history of the flow of electrons in semiconductor devices. Let us discuss the history of electronics. In earlier, Scientists started to imagine how to transform the Alternating current to direct current. Because producing the direct current is very costly. Then they enter into the vacuum tube. In 1904, James Ambrose Fleming, developed the first vacuum tube. Fig.1 show the basic structures of the vacuum tubes.
Fig.1 Vacuum Tubes
The vacuum tube is used as a rectifier to convert alternating current to direct current i.e., known as Edison effect. The diode is the simple design of a vacuum tube. They are two electrodes, i.e., anode and cathode. When the cathode gets warmed, the electrons are delighted. The delighted electrons have the potential to carry off the cathode into the vacuum. There will be current flow across the tube when the electrons is attracted towards the anode (plate). The invention of a two-terminal vacuum tube paves the way for the history of electronics.Later, Triode is a three terminal vacuum device invented by lee de forest and Robert von lieben in 1906. The Triode is used as an amplifier that converts the weak AC to a strong AC signal. Then these devices were used in radio transmitters and receivers. It was incredibly power-hungry, as the vacuum tubes cathode needed to be heated to work, which also meant that the vacuum tube burnt out regular and needed to be replaced.
- Semiconductor Era:
Fig.2 First Transistor
To overcome the disadvantages of vacuum tubes, Semiconductor based devices are invented. The invention of the Semiconductor made a great revolution in the electronics industries. In 1947, The Transistor was discovered by three researchers John Bardeen, William Shockley, William Brattain in Bell Labs at USA. When a germanium crystal is applied with two gold point contacts that produce an amplified signal with higher power i.e., First Bipolar Transistor, it is represented in Fig.2. John R. Pierce built a term as Transistor . The word Transistor comes from the combination of transconductance + transfer + varistor. In 1956, They got a Nobel Price in physics for the discovery of Transistor. Modern electronics began from the invention of the Transistor. After the creation of Transistor, an independently new branch is introduced in the engineering field, i.e., electronics engineering. It is thoroughly distinct from electrical engineering.
Fig.3 Electronics components connected with wires
Initially, the electronic circuits are designed by connecting the discrete components through the wires, Fig.3 shows the connection of simple circuit. In total circuits, 60 % of the place is occupied by the wires only. It would have make the device bulkier. So the PCB concept is introduced. Compared to the wired circuit, PCB is high reliability and small in size.
2.1: Integrated circuit Era
Fig.4 .First integrated circuit developed by Texas Instruments and modern IC
Day to day life, the users require electronics gadgets of small size and less power consumption so that the scientist tried to put the number of components into a single chip.Jack Kilby of Texas Instruments first invented integrated Circuit in 1958 and it is represented in Fig.4. The IC combines a Transistor, capacitor, resistor, which looks like a chip of a single wafer. In the semiconductor industry, the manufacture of silicon IC’s are improved. In mid 1970, ’s the digital integrated circuits were made first but analog IC in large scale integration and VLSI were followed. VLSI as a single chip consists of 1000’s of switches and gates. IC’s are used in the manufacture of Microcomputers, medical equipment, video cameras, the communication satellite etc. In 1965, the co-founder of Intel, Gordon E.Moore marked that the number of transistors on integrated circuits multiplied every two years; this flow has held very recently, but it is beginning to hold back. The leading cause for this is Moore’s prediction. At present nearly 8 billion transistors are fabricated in Intel Core I9 processor.
Fig.5 Core i9 processor
- Advanced Electronics Devices:
3.1 High Electron Mobility Transistors:
Moore’s second law or rocks law which orders that the cost of manufacturing these devices will double every four years. Another problem that the transistors are exposed is quantum tunneling. As these transistors get smaller, barriers is formed between different sections. The barrier between each section of the Transistor is getting so thin that electrons can drift through them. Intel said that they discussed shifting their focus from extending in speed and lower power consumption. The computer industry has to redefine itself shortly.Takashi Mimura and colleagues develop HEMT at Fujitsu in Japan. The HEMT is a type of field effect transistors (FET), which offer a combination of low noise and very high performance at microwave frequencies. Fig.6 show the structure of the GAN device.
Fig.6 GaN device structure
HEMT is used in low noise amplifiers, radio telescope, space and military applications, satellite broadcasting receivers, telecommunications, instrumentation, and RF design. At very high RF frequencies high performance is needed. The familiar materials used in HEMT are Aluminium Gallium Arsenide(AlGaAs) and Gallium Arsenide (GaAs). Normally Gallium Arsenide is used because it supports higher mobility and high carrier drift velocities than Si.
3.2 Silicon Nano Wires
Fig.7 Silicon Nano Wire transitory and its applications
In CMOS devices due to short channel effects and large power dissipations, the Moores law is currently ending. Alternatively the Silicon Nano Wire Transistors (SNWT) are proposed instead of conventional planar technology. This SNWT has the improved electrostatic control over the channel and reduces the short channel effects. The Fig.7 show Silicon Nano Wire transistor and its applications
3.3. Carbon Nano Devices:
A carbon nanotube (CNT) is a graphene sheet rolled up to form a hollow cylinder; carbon atoms appear in a hexagonal pattern. In CNTs, the electrons can move inside the tube without scattering. Due to this, CNT has low electrical resistance and less power consumption.
Fig.8 Wearing carbon nanotube based electronics devices on skin
The principal applications of Carbon Nano Tube is the wearable electronic systems. This type of devices are integrated into our dresses and skin patches as per Fig.8. However, one of the main issues in constructing these flexible electronics is using inorganic semiconductor materials such as Si or GaN for the channel and dielectric respectively: But the main drawback of this carbo