Other characteristics of transistors as that, for example, at temperature increase on 10 degrees current of Ikbo increases twice also depend on temperature that breaks an operating mode of the transistor towards big currents. Therefore in the industry transistors from more heat-resistant materials (kremniyeva and various methods of cooling of the scheme are used.
Nonbasic carriers freely pass through internally field p-n of transition since it for them is dispersing, and make conductivity current (drift. The main of the carrier, overcoming a diffusive field, create diffusive current. In the absence of an external field diffusive current and current of drift are equal. Such state is called equilibrium.
Semiconductors call group of elements and their connections at which specific resistance takes an intermediate place between conductors and dielectrics. Initial material for production of semiconductor devices are elements of the fourth group of periodic system of Mendeleyev (silicon, Germany, etc.), and also their connections. All of them are crystal substances under normal conditions.
In the first part of material the reasons which force to pass to new technologies of memory are described. The description of six main technologies, their similarities and distinction is provided in the second part of article. Need of increase in productivity of system of memory.
It is the most known to us a way of storage of information. Its essence consists in magnetization of areas on the carrier (a tape, a disk and then reading of existence \lack of magnetization. Stores on magnetic tapes now departed in the past because of the lowest speed information searches, and disks are used and is the up to that moment widest.
The hole (the blank covalent communication) can be filled with the electron which left the next covalent communication. One covalent link is broken, another – is restored. Thus the impression turns out that the hole moves on a crystal. The rupture of covalent communications as a result of which the free electron and a hole are formed is called as generation, and restoration of covalent communication – a recombination. The recombination is followed by allocation of some quantity of energy, and a recombination – absorption.
However, bipolar transistors possess very small entrance resistance and a high lag effect. Therefore in computers generally field transistors, which are used (to that miniaturizations give in much easier. Bipolar transistors give bigger speed.
In total. It was necessary only to lay metal connections on a chip surface (today for this role aluminum is usually used, and connections are usually located in the 6th layer today, and it's done. In general, so in result, for example, classical MOP the transistor also turns out: in the presence of tension on a lock movement of electrons between the changed silicon areas begins.
If puts tension of the return orientation (so-called return inclusion, intensity of the internal field p-n of transition increases, diffusive currents decrease practically to zero (the potential barrier grows). Drift current practically does not change the value. There is the return current – Iobr which is proportional to number of neosnovy carriers in the semiconductor and much less (approximately on 6 about direct current. Thus, it is possible to consider that the semiconductor with p-n transition has unilateral conductivity.
The basic for pure semiconductors is the n-type since electrons have big mobility. If to bring in the semiconductor atoms with lower valency (so-called acceptors), than the semiconductor, it will get p-type since low-valent atoms willingly will absorb free electrons.