Which semiconductor material is made from coal ash

The recent trade disputes with the U. To avert a looming trade war with the U. A former Huawei employee has accused the company of trying to steal intellectual property to help China achieve technological dominance over the US. Huawei and its FutureWei unit sued Huang and his start-up CNEX Labs last December, accusing Huang of making off with sensitive trade secrets related to semiconductor technology that uses integrated circuits as memory to store data.

Huang, in a response filed on Tuesday, said Huawei got it backward. He claims he was hired so the Chinese company could take control of his inventions for Solid State Disk Non-Volatile Memory and then, after he left, sought to obtain proprietary information from his new company. This lawsuit goes beyond semiconductor technology, however. Now as we move away from the tensions between China and the U. It is widely predicted the doubling of silicon transistors per unit area every two years will come to an end around as the technology reaches its physical limits.

However, researchers at RMIT University in Melbourne, Australia, believe a metal-based field emission air channel transistor ACT they have developed could maintain transistor doubling for another two decades. The ACT device eliminates the need for semiconductors. Instead, it uses two in-plane symmetric metal electrodes source and drain separated by an air gap of fewer than 35 nano meters, and a bottom metal gate to tune the field emission.

The nano scale air gap is less than the mean free path of electrons in the air; hence electrons can travel through the air under room temperature without scattering. Unlike conventional transistors that have to sit in silicon bulk, their device is a bottom-to-top fabrication approach starting with a substrate. This enables them to build fully 3D transistor networks if they can define optimum air gaps.

This essentially means they can stop pursuing miniaturization, and instead focus on compact 3D architecture, allowing more transistors per unit volume.

Using metal and air in place of semiconductors for the main components of the transistor has many other advantages, as well. Fabrication becomes essentially a single-step process of laying down the emitter and collector and defining the air gap. Consequently, production costs should be cut significantly. Replacing silicon with metal means these ACT devices can be fabricated on any dielectric surface, provided the underlying substrate allows useful modulation of emission current from source to drain with a bottom-gate field.

Machines can be built on an ultra thin glass , plastics , and elastomers so that they could be used in flexible and wearable technologies. Ancient processes caused Germanium to become somewhat concentrated in certain Coal seams, and, once the Carbon has been combusted for whatever purpose, the Ash from that Coal contains recoverable Germanium in concentrations higher than the Lead and Zinc ores from which it is currently being produced.

Shahbaz Ali said: Dec 28, Carbon is the correct answer. Current Affairs Interview Questions and Answers. Roopali Thakurta said: Oct 23, Please any one help me with the relation between coal ash and germanium!

Anusha said: Apr 10, Yashu Swami said: Jul 11, I think graphite would have been a better option. Shwetha said: Sep 6, Coal consists of carbon, then how can we say its germanium? Reena said: Feb 4, Sumanth Punda said: Apr 24, Yamini said: Jul 19, Of course the coal consists of carbon.

Rohini said: Jan 12, Apeksha said: Feb 3, So what that mean? This is why such dopants are called acceptors. The dopant atom accepts an electron, causing the loss of half of one bond from the neighboring atom and resulting in the formation of a "hole". Each hole is associated with a nearby negatively charged dopant ion, and the semiconductor remains electrically neutral as a whole.

However, once each hole has wandered away into the lattice, one proton in the atom at the hole's location will be "exposed" and no longer cancelled by an electron. This atom will have 3 electrons and 1 hole surrounding a particular nucleus with 4 protons. For this reason a hole behaves as a positive charge. When a sufficiently large number of acceptor atoms are added, the holes greatly outnumber thermal excited electrons.

Thus, holes are the majority carriers, while electrons become minority carriers in p-type materials. When an electron jumps from the valence shell to the conduction band, it leaves a gap. What is this gap called?