New Semiconductor Materials and Impurity Defects

I Wide Band Gap Semiconductor Materials Gallium nitride, silicon carbide, and zinc oxide are all wide bandgap semiconductor materials, because their forbidden bandwidths are all above 3 electron volt…

I Wide Band Gap Semiconductor Materials

Gallium nitride, silicon carbide, and zinc oxide are all wide bandgap semiconductor materials, because their forbidden bandwidths are all above 3 electron volts, and it is impossible to excite valence band electrons to the conduction band at room temperature. The operating temperature of the device can be very high, such as silicon carbide, of which temperature can reach 600 degrees Celsius. If a diamond is made into a semiconductor, the temperature can be higher, and it can be used to collect relevant information on an oil drill probe.

They’re also applied in harsh environments such as aviation and aerospace. The only high-power transmitting tube of radio stations and television stations is still electron tubes not semiconductor devices. The life of this kind of tube is only two or three thousand hours, it is bulky, and consumes a lot of power. If we use silicon carbide high-power emitting devices, the volume can be reduced by at least tens to hundreds of times, and the service life will be greatly increased. Therefore, wide bandgap semiconductor materials are very important new semiconductor materials.

However, this material is very difficult to grow. It’s easy to grow silicon on silicon and grow GaAs on gallium arsenide, but most of this material does not have a bulk material, and we have to use other materials as the substrate. For example, gallium nitride is generally grown on a sapphire substrate. The thermal expansion coefficient and lattice constant of sapphire and gallium nitride are very different so that the grown epitaxial layer has many defects, which is the biggest problem and difficulty at present. In addition, processing and etching of this material are also very difficult. Scientists are working to solve this problem for a more broad space for new materials.

II Low-dimensional Semiconductor Materials

In fact, the low-dimensional semiconductor materials mentioned here are nanomaterials. One of the important purposes of developing nanometer science and technology is to control and manufacture powerful of nanoelectronics, optoelectronic devices and circuits, nano-biosensors, etc. with superior performance to benefit humans on the scale level of atoms, molecules and nanometers. It can be expected that the development and application of nanotechnology will not only completely change people’s production and life, but will also change the socio-political pattern and forms of confrontation in war, which is why people attach great importance to the development of nano-semiconductor technology.

The electrons in the bulk material can move freely in three dimensions. But when the feature size of the material is smaller than the mean free path of the electron in one dimension, the movement of the electron in this direction will be limited, and the energy of the electron is no longer continuous, but quantized. We call this material a superlattice, quantum well material. For quantum wire material, the electron can only move freely along the direction of the quantum wire, and the other two directions are restricted. And in quantum dot materials, the size of the material in three dimensions is smaller than the mean free path of the electrons. The electrons cannot move freely and the energy is quantized in all three directions.

Due to the above reasons, the state density function of the electron has also changed. The state density function of bulk material is a parabola, and the electrons can move freely on it. If it is a quantum dot material, its state density function is completely isolated distributed, which is the same as a single molecule or atom. Powerful quantum devices can be manufactured based on this feature.

The memory of LSI is realized by charging and discharging a large number of electrons. The flow of a large number of electrons requires a lot of energy, causing the chip to heat up, which limits the degree of integration. If a single or several electrons are used for memory, not only the integration degree can be improved, but the power consumption problem can also be solved. The efficiency of lasers is not high, because the wavelength of the laser changes with temperature. Generally, the wavelength is red-shifted as the temperature increases, so in fiber-optic communications, the temperature of the laser must be controlled. If quantum dot lasers can be used to replace existing quantum well lasers, these problems will be solved.

GaAs and InP-based superlattices and quantum well materials have developed very maturely and are widely used in the fields of optical communications, mobile communications, and microwave communications. Quantum cascade laser is a kind of unipolar device, which is a new type of mid- and far-infrared light source developed in the past ten years It has important application prospects in free-space communication, infrared countermeasures and remote-control chemical sensing. It has high requirements for the preparation process of MBE(molecular beam epitaxy), and the entire device has hundreds to thousands of layers, and the thickness of each layer must be controlled to a few tenths of nanometers.

III Impurities and Defects in Semiconductor Materials

Most of the methods of impurity control are doping a certain number of impurity atoms when the crystal grows. The final distribution of these impurity atoms in the crystal depends not only on the growth method itself, but also on the choice of growth conditions. For example, when the crystal is grown by the Czochralski method, impurity segregation and the irregular convection in the melt will cause fluctuations in the impurity distribution. Besides, no matter which crystal growth method is used, impurities will be introduced into the container, heater, ambient atmosphere and even the substrate during the growth process. This situation is called the autodoping. Crystal defect control is also achieved by controlling crystal growth conditions, such as the symmetry of the thermal field around the crystal, temperature fluctuations, environmental pressure, growth rate, etc., With the decreasing of the device size, there is also a limit to the microcell unevenness of impurity distribution in the crystal and the small defects of the order of atomic magnitude. Therefore, in the process of semiconductor materialsFind Article, how to carefully design and strictly control the growth conditions to meet the various requirements for impurities and defects in semiconductor materials is the central issue.

Life Is Not About Finding Yourself But Creating Yourself

Life is how we make it. Be that as it may, however many humans are experiencing their lives alongside these strains. Regardless of whether or not deliberately or unknowingly we disengaged from our potential, substance and soul to land up feeling at some degree lost. Possibly it takes place while we seem to have all that we want superficially; cash, assets, achievement, yet we want delight at the most profound level.

At some instances, we feel lost and confounded along these traces, it is our consciousness to wake us up to the truth of who we definitely are; divine limitless creatures which might be incredible, unfathomable. The saddest element is that people may by no means song in to this call from soul. A sizeable number folks are so molded, so dozing to our personal beautiful pressure that it’s excessively startling. Rather than grasping our potential, we deviated our cognizance.

On the other hand, when we’re open and aware of revealing our fullest potential, we boom an extremely good hazard to benefit proficiency with the embodiment of what it actually intends to make our life. The manner we select here is the component that makes a decision the direction of our future, and affects our potential to without a doubt mission into our most noteworthy possible articulation. The unmarried best change we are able to hold close now in our lives is to count on radical legal responsibility for who and where we are now.

From this point onward, we emerge as open to development, extension and the solving of the whole lot of the restricted views and being we’ve got utilized before. Assuming liability for your lifestyles along these strains takes HUGE measures of intellectual fortitude. It might be awkward on occasion to decide to be the realistic maker of our reality, because it implies there is by no means once more any other person responsible for the matters we don’t care for. What is unmistakably increasingly awkward however is wearing on with an real lifestyles path underneath our capacity due to the fact that we in no way had the mental fortitude to assume legal responsibility for our lives.

Every individual holds a specific perspective about lifestyles due to our distinct manner of wondering and attitude towards existence. I agree with it is up to us to create our role in it. Life is all approximately discovering our actual self. It is high time to prevent finding yourself and go in advance to creating yourself.

In fact, we lose our real essence due to the fact we need our society to accept us, so we change, and compromise. But while we spend few moments to reflect, we found out that it’s miles important that we create our personal identity. Every desire we make matters. To form our lives like the manner we need it, we want to make bold alternatives to obtain our goals despite the fact that it method taking the road less traveled. We need to make decisions that convey us closer to our goals of making a call for ourselves.

What is The Best Time to Invest in Gold

This article discusses what asset class does gold belong to, what are its characteristic and trend behaviour. It also outlines what is the best time to invest in gold for both long term and medium term investors

This article seeks to set down what is the best time to invest in gold.

We will firstly determine the asset class that Gold fits into. Seondly, we will list down its characteristics and trend behaviour . Thirdly, we will discuss how does gold investment fit into your overall portfolio. Last but not least, we will nail down the all important question of What is the best time to invest in gold.

Asset Class

Generally, there are a few asset classes for your investment portfolio which you would need to be aware of. They are cash or cash equivalents, equities, bonds, real estate, commodities. Moreover, these can be further divided into sub classes. For example, commodities can be broadly divided into 3 sub classes of Precious Metals, Energy and other commodities, simply because all 3 have slightly different characteristics which justifies further classification. We can also divide equities into 3 sub classes. They are defensive stable dividend paying stocks, growth stocks, high risk speculative new venture stocks

For a balanced portfolio, it is always advised that you have some investments in all of the above mentioned classes.

So, which asset class does gold fall into. Gold is a very unique asset. It falls under the commodity class and specifically the precious metals sub class. However, it also can be cash or cash equivalents, as a universal store of value. In this respect, it can be traded as a forex pair like XAUUSD, XAUJPY.

Characteristics and Trend Behavior

We will discuss the characteristics for gold as an precious metals asset class, characteristic for gold as an cash or cash equivalent and its trend behaviour

Characteristic of Gold as a Precious Metal

The main characteristics of the commodity class is that it does not pay anything for holding it. It does not bear interest. Neither does it pay dividend. You make a profit mainly from the difference in the price you bought and the price you sell.

Another characteristic is that its value is primarily driven by market demand and market supply. For example, in the case of soy beans, when demand shifts up, the price goes up. And if, there is a supply shock, for example natural disasters affecting soy bean plantation, the price goes up too.

Another characteristic is that there is physical delivery of the commodity that is purchased.

However, Gold is also part of the sub class of Precious Metals which has an additional characteristic of this sub class. This is limited supply. Because it is mined, there is a limit to how much supply there is. You will find that this is especially so for the case of gold. So, in the case of gold, its price is determined more on the demand side, rather than the supply side.

Characteristic of Gold as Forex

On the other hand, its value is also determined by performance of other currencies. That is, when there is a crisis in Japan, gold expressed in japanese yen would go up much more.

Trend Behaviour to determine what is the best time to invest in gold

Gold will reacts to the following factors, namely crisis, currency devaluation and period of high inflation

a. Crisis

In periods of severe crisis, its appeal as a safe haven would cause the price of gold to skyrocket. This is because it is universally accepted and is impervious to what happens in the world. Therefore, in a crisis, when confidence is eroded, flight to safety would mean funds will start flooding into gold

b. Currencies devaluation

During times when fiat currencies are devalued, Gold will automatically rise against such currencies. So, for those who are in countries where their currency is being devalued, the best way for them to preserve their wealth is through gold holdings.

c. Period of high inflation

You will also find that Gold performs exceptionally well in times of high inflation, especially due to supply shocks. You will notice that it rocketed during the 1970’s oil crisis. What’s more, you see that it made an all time high (in real terms) in 1981 before drifting back down.

Furthermore, you will notice that inflation was going through the roof during that time. So much so, that the Fed chief at that time have to increase interest rates dramatically to curb it.

How It fits into your overall portfolio

You should have some exposure to gold as part of your portfolio. Gold is usually counter-cyclical. When equity prices is high and gold prices are low when the economy is steaming ahead, you would need to rebalance your portfolio. This is done by cashing out some of your other investments which seems over-extended and put into gold. This is to protect your overall investment portfolio, when troubles come and equities are taking a beating, your gold investment can help.

What is the best time to invest in gold

I believe you would have already guessed it from the above.

For long term investors

For long term investors, the best time to invest in gold would be during periods of calm before the storm. This is the time when the price of gold would be lowest. During this period, slowly accumulate gold. Hold off or slow down your purchases when the storm breaks. When the storm seems to being resolved, you can either opt to sell a portion of your holdings to lock in profits or wait for prices to come down before accumulating again.

For medium term investors

For medium term investors, the best time to invest is at the first sign of trouble and to get out at the first sign of resolution of trouble.

How to Start Investing

I prefer to invest in physical bullion for the long termFree Web Content, whilst engaging in short term trading in the forex pair XAUUSD.

You can download a free gold investment kit here to help you get started in physical bullion investing.