PN JUNCTION PDF
The p-n junction is the fundamental building block of the electronic age. Most electronic devices are made of sili- con. By exploring the electrical properties of. Semiconductor material doped with donors. Material has high concentration of free electrons. Concentration of holes in n-type material is very low. p-n junction. No current / thermal equilibrium. •PN Junction at equilibrium. 1st Step: diffusion mechanism. 2nd Step: built in Electric Field appears⬄ compensates diffusion.
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Before going to the discussion of diode, we have to check the details of P-N In a step graded P-N junction, there exists a concentration gradient near the. One important feature of the pn junction is that current (holes) flows freely in the p to n direction Typical I-V static characteristics of a silicon pn junction diode. The p-n junction is a versatile element, which can be used as a rectifier, as an isolation structure and as a voltage-dependent capacitor. In addition, they can be .
Dunlap, Jr. Pearson, B.
Multiple Choice Questions (MCQs)
Sawyer: Silicon p-n junction alloy diodes. Teal, E. Buehler: Growth of silicon crystals and of single crystal silicon p-n junctions. Frank, V. Gummel: Hole-electron product of p-n junctions.
Multiple Choice Questions PNJunction
Solid State Electron. Dermenzhi, A. Herlet: The maximum blocking capability of silicon thyristors. Solid-State Electron 8, Google Scholar 3. Zener: Proc. London , CrossRef Google Scholar 3. Sze, G. Esaki: New phenomenon in narrow germanium pn junctions. Kane: Theory of tunnelling. Kane: Thomas—Fermi approach to impure semiconductor band structure. Chynoweth, V. Feldman, R.
Logan: Excess-tunnel current in silicon. Esaki junctions. Herlet: The forward characteristics of silicon power rectifiers at high current densities.
Solid-State Electron. Spenke: Notes on the theory of the forward characteristics of power rectifiers. Hall: Power rectifiers and transistors. Burtscher, F. Davies, F.
For irradiated p—n junction diode, current—voltage curve has still rectifying behaviour but exhibits lower turn-on voltage than that of virgin p— n junction diode. Though, certain materials simultaneously fulfil the requirements of favourable conductivity and transparency. An important criterion for materials that can be used in these applications is that they possess a high optical transparency in the visible range of the electromagnetic spectrum and high electrical conductivity.
Combination of conductivity and transparency in oxides is achieved by fabricating them with a non-stoichiometric composition or by introducing appropriate dopants. Among various oxide semiconductors, tin oxide, zinc oxide, titanium oxide, nickel oxide are particularly attractive materials [2—8].
In this work, Fe-doped SnO2 was used as n-type conducting oxide. Because of its good adsorptive properties and chemical stability, it can be deposited on glass, ceramics, oxides, and substrate materials of other types.
It has a high melting point and good transmission of light in visible region of electromagnetic spectra, and it does not easily react with oxygen and water vapour in the air, so it has a high specific volume and good cycling performance . On the other hand, lithium-doped nickel oxide Li:NiO has been used as a p-type semiconductor. NiO is a wide band gap semiconductor at room temperature [10, 11]. It has been demonstrated that change in electric properties can be induced by swift heavy ion irradiation SHI in binary oxides such as Li-doped NiO thin film  and In2O3 thin film .
There are reports on irradiation effects on SnO2 thin film for modifying its optical, electrical, Page 2 of 8 morphological, and gas-sensing properties.
It is possible to tune the properties by irradiating SnO2 thin film to particular ion fluences. Although, there are reports on the effects of ion irradiation on SnO2 thin film, there are no reports available on the irradiation effects on the diode structure based on Fe-doped SnO2 [14, 15]. For device fabrication, defects induced in semiconductor by radiation play an important role. The SHI irradiation of thin film has been subject of research because SHI can modify optical, electrical, and optoelectronic properties .
For SHI irradiation, the extent of damage formation and property modification depends strongly on energy, mass, and fluence of the ion and target density.
Deposition of oxide semiconductors using pulsed laser deposition PLD under ultra-high vacuum UHV offer impurity-free environment as well as smooth interface with excellent stoichiometric control . The fabricated p—n junction diodes were irradiated with O? Pristine SnO2 is an n-type semiconductor having very low conductivity. Transition metal doping such as Fe2?
On the other hand, higher doping levels of Fe would degrade its optical transparency. Moreover, low or dilute doping is also desirable for preserving the single crystallographic SnO2 phase [5—7]. Earlier, we have shown that 10 at. The laser pulse repetition rates and laser powers were fixed at 10 Hz and 2.
Substrate temperature of B. Mistry et al. The samples were mounted on irradiation ladder in a high-vacuum chamber. In order to do homogeneous irradiation, the ion beam was carefully scanned over an area 1 9 1 cm2 using electromagnetic scanner. The diameter of the ion beam was 2 mm to 3 mm.
Since the range of oxygen ions in the target materials is about The observed material modifications are expected only due to the defect induced by the passage of ions through the film.
Highpurity Ag was deposited by e-beam evaporator Vacuum Techniques Pvt. Microstructural investigations of pristine and irradiated samples were done by grazing angle X-ray diffraction GXRD and atomic force microscopy AFM measurements. The optical measurements of the films were carried out at room temperature using a Shimadzu UV—Vis spectrophotometer. All measurements were taken at room temperature.
The electronic stopping power Se of 80 MeV O? The nuclear stopping, which is an elastic process, creates vacancies and interstitials through the transfer of energy to the target lattice that results in atomic displacements in the form of Frankel defects.
On the other hand, the inelastic electronic stopping process transfers a large amount of Page 3 of 8 energy to target lattice through electron—phonon interactions. The size of the grains before irradiation appears to be uniform.
After irradiation by 80 MeV O? However, the average surface roughness of the films increases. Increase in the film roughness due to ion irradiation is typical for variety of oxide film [14, 15, 18].
Formation of a PN-Junction
It is primarily due to high-energy deposition of individual ions and flux on the surface through electronic potential that results in distinct features such as grain splitting and formation of hillocks.
For a Fig. For pristine sample, particle distribution was found uniform. Particle size decreases on irradiated and also they were elongated Page 4 of 8 B.
However, quantification of such an attribute requires different energy ions at various fluence values. In brief, the different increase in roughness for the two films upon irradiation is assumed to be due to different radiation resistant properties of the SnO2 and NiO thin films.In fact, since the y-axis of figure A is log-scale, the region is almost completely depleted of majority carriers leaving a charge density equal to the net doping level , and the edge between the space charge region and the neutral region is quite sharp see figure B , Q x graph.
Among various oxide semiconductors, tin oxide, zinc oxide, titanium oxide, nickel oxide are particularly attractive materials [2—8]. Pristine SnO2 is an n-type semiconductor having very low conductivity. Care and special treatment is called for only in places where the pn junction contacts the surface of the crystal.
Once the electric field intensity increases beyond a critical level, the p—n junction depletion zone breaks down and current begins to flow, usually by either the Zener or the avalanche breakdown processes.
Handbook of Photovoltaic Science and Engineering. Such oxygen loss may be small enough to be detected by EDX but it is sufficient to influence on the I— V characteristics. This page was last edited on 14 April , at Therefore, very little current flows until the diode breaks down.