Junction Definition and 200 Threads

Hi, I need help to understand this section from my book. Here we are considering drift current Is of PN junction under open-circuit conditions. I don't understand why the drift current Is is indepentent of the value of the depletion layer voltage Vo. I think the voltage create an...

Homework Statement Calculate the width of the space charge region in a pn junction when a reverse biased voltage is applied. Consider a silicon pn junction at T=300K with doping concentrations of Na=10^16 cm^-3 and Nd=10^15 cm-3. Assume that Ni=1.5*10^10 cm-3 and VR=5V Homework Equations...

I need help to understand this solution: Why electric field is zero at x < - b? I think it should be non-zero because the electric field from positive and negative ions don't completely cancel each other. How can you know E rises as x approaches zero?

what is it ? please explaining the physical operation of semiconductor diode (pn junction).

We have been looking at P-N junction diodes in our lab session this week and investigating the current through the circuit and how this relates to the Voltage. We are using the approximation: I = (I0)*exp(qV/kT) We measured the voltage and the current for a few different voltages and this...

I know this is true under thermal equilibrium, but I am not sure why. Why can't the Fermi level be a function of position relative to the pn-junction? How does that follow from thermodynamics/statistical mechanics?

Homework Statement The forward bias current I in the diode described (silicon p-n junction) varies as a function of the voltage V and temperature T described by the formula I = I_s*|e^[(|e|*V]/[n*k_b*T]) - 1| where |e| is the fundamental charge, k_b is the Boltzmann constant, I_s is the...

Homework Statement Two straight roads intersect at point O and cross at an angle Θ to one another, such that tan Θ = 3/4.Two cars, A and B are traveling towards O on these roads,A at 5 m/s and B at 8 m/s At a certain moment.A is 100 m from the junction and B, on the other road, is 200 m...

Hi, I am interested in a junction between n doped and intrinsic GaAs, specifically the localization and width of the depletion zone (where the built-in E field is). In a p-n junction the depletion zone is calculated under the condition of electro-neutrality, if I see i-GaAs as really really low...

Hi, I'm stuck with the electrostatics of the PN junction. I just can't see why the electric field has to be negative in the depletion regio. The two equations give positive values for the Electric field in the intervals, so how can it be negative?? In the equation for the n regio, there are...

Homework Statement The drift current in a p-n junction is 20μA . Estimate the number of electrons crossing a cross section per second in the depletion region. Homework Equations Drift current is the current that occurs due to formation of holes and electrons in the depleted region from...

why the potential of n side is higher than that of the p side when no battery is connected to the p-n junction?

In particular, I am looking at a datasheet of a PNP BJT: http://www.fairchildsemi.com/ds/2N/2N3906.pdf I noticed that in the ON CHARACTERISTICS sub-heading, there were multiple h_{FE} values. I'm wondering how I could extract any meaningful information from that since the most common h_{FE}...

Hello everyone. I have a couple of questions about the depletion region in the p-n junction 1) Why don't the negative ions on p-side of the depletion region donate their respective extra electrons to the positive ions on the n-side of the region so they can both be happy (This sounds kind of...

Hello guys , beside Einstein's General Theory of Relativity by hervik , is there any lecture or book about this case ? Thx

Hi All, I am trying to get my head around the energy band diagrams associated with forming a metal-semiconductor junction for both p and n type s/c. I am also consider for each type, the case of \phim > \phin (work function of metal greater than work function on s/c) and \phim < \phin (work...

Hi, on re-visiting some basic ideas about PN junctions, I found I am confused with the depletion region diagram: I understand that the depletion region originated from the diffusion current at the local contact of the p and n type material, the electrons diffuse from the n type to p type...

Hi the first step to this is usually described as diffusion of electrons from the n type to the p type. However I have encountered sites and books that state that holes diffuse from p type to n type as well. I am of the opinion that only the electrons diffuse, and that there is no diffusion of...

I've been reading various explanations for a number of hours, and I'm still completely confused. I'll refer to an explanation from Wikipedia, but do point me to a better one if you know one. What does the depletion zone have to do with current flow? Looking at Figure A (see link above), there...

Hi. I am reading about the pn junction, but I have a question. When the junction is formed the holes in the p-type material close to the junction diffuse across due to the concentration gradient. This leaves the acceptor atoms in the p-type material negatively charged. My question is: when...

Why does the depletion layer penetrate a lightly doped side of a p-n junction diode?? Consider that there is a lightly doped p-side and a heavily doped n-side in a p-n junction diode , which is connected to a dc power supply in reversed biased. Now, I've read that depletion layer penetrates the...

Why exactly is there zero current flowing through a diode when it is short circuited, given the presence of the barrier potential? My current understanding is that the drift current precisely balances the diffusion current. But if you take a diode and short it with a wire, wouldn't you then also...

When electrons from N region diffuse to P region, the electrons combine with holes to form a -ve negative ion leaving behind a +ve ion in P region.So, my doubt is how the holes accept the electrons and get a negative charge because as the holes are positively charged, when they accept the...

I am having a hard time to find answers to 2 simple questions regarding semiconductors. Firts, at a PN junction diffusion creates a potential step. Why can this voltage not been measured from the outside. The schoolbook answer is, that there are diffusion potential at the wire connections...

Hello Forum, I am looking at the energy levels between the n and p regions of a diode. The p-side has a conduction band that starts at a higher energy (same for the valence band). The n-side has the valence and condution bands that are at lower energy. The Fermi energy line is the same...

Homework Statement I've been reading and I just want to make sure that this is the correct way which pv cells work, I feel this is not correct. I want to find where I am wrong. Once the p and n doped semiconductors are put together some carriers migrate and combine to form a depletion zone...

Q:-Find the current through the resistance R in the figure:- , if the value of R is:- a.12Ω b.48Ω. Assume resistance offered by diode is 0 in forward bias and ∞ in reverse bias. Homework Equations Ohms Law:- V=RiThe Attempt at a Solution I tried using kirchhoffs law but we don't know its in...

When a metal is brought into contact with a semiconductor (n-type) a depletion layer is formed at the metal-semiconductor interface on which band bending occurs. In the full-depletion model it is assumed that all donors are positively charged (withi this layer). What happens if a back-gate (with...

Are there any known gap junction openers/closers for C. elegans? I've googled far and wide for weeks. Trimethylamine, quinine, and carbenoxolone are known to work with connexins in mammals. They also happen to be expensive and require more paperwork, so I don't want to go through the steps...

Hi, Can someone please tell me if it is true that in heavily doped pn junctions, the electric field that prevents further diffusion of holes and electrons is set up more quickly than in less heavily doped pn junctions? Is this essentially because the holes and electrons recombine more...

Homework Statement Calculate the current i5 in the configuration. Use the following data: i1=8.65 A, i2=5 A, i3=7.85 A, and i4=8.5 A. Homework Equations Kirchoff's junction rule states that the sum of the currents meeting at a junction has to equal zero. The Attempt at a Solution...

Hi friends, here's my question. The two terminals of a PN junction are at different potentials so, if I connect a them with a wire i.e. short them, What would happen? Would the potential difference between the two ends becomes zero or what? As far I'm understanding, there would be a flow of...

For p-n junctions (connected as a junction rectifier), the forward-bias connection (battery's positive terminal connected at the p side) results in a narrowed depletion zone, because: the p side becomes more positive and the n side becomes more negative, thus decreasing the height of the...

Homework Statement Use Kirchhoff's junction rule to calculate the current supplied by the battery. Homework Equations attached a pic. The Attempt at a Solution Where do we start?

Homework Statement A girl needs a rod that will carry heat from a pan of boiling water to a mixture of ice and water so that the ice will melt more quickly. She has a copper rod of diameter DCu and an aluminum rod of diameter DAl, neither of which is long enough to reach from the pan to the...

Given this picture, the circuit is put in reverse bias. Therefore the electrons are flowing INTO the p-type junction. - As electrons flow into the p-type material the depletion zone is raised as the p-side is made more negative. A picture from hyperphyics.phy-astr.gsu.edu illustrates this...

Show how two P-N junction diodes can be used in conjunction with a transformer that has two secondary windings, to form a full-wave rectifier. (Draw a circuit diagram including connections to the mains transformer). Explain the operation of your circuit using sketches of waveforms. (3 marks)...

[FONT="Times New Roman"][SIZE="3"]When the NPN is in the forward active mode The base emitter junction is forward biased and the base collector junction is reverse biased. But isn't it possible for the base collector junction to break down? Or do we assume it never breaks down? Also does...

hi everyone, i have discussed this problem with some other people but couldn't understand it well because of my own limited knowledge and understanding of such things. then i sent an email to my very dear teacher and a friend. email copy and my teacher's reply is below. now the problem is i...

Homework Statement A semiconductor p-n junction is fabricated where the doping concentration on the p and n sides of the junction is Na=1E18cm^-3 and Nd=1E16cm^-3 respectively. Given that ni=1.18E10cm^-3, T=300k calculate: a) The majority and minority carrier concentrations in the...

[PLAIN]http://img96.imageshack.us/img96/7816/12530747.jpg Hopefully this will post successfully... Erm its the first part I'm not sure on, after that it's easy. I'm just not understanding the wording. I need to work out the effective green time during the cycle

[FONT="Times New Roman"] [SIZE="3"]When a PN juction is in the open circuit condition, my textbooks says the following. "The voltage measured between the terminals is zero. That is the junction Voltage Vo does not appear across between the diode terminals.This is because of the contact...

I am studying to become and electrical engineer and am currently taking Electronics I. I am having trouble understanding the change in the depletion region that results from a bias. I understand that at the time of manufacture the free electrons from the n-type semiconductor are attracted to the...

Hi I'm practising past papers however have no answers. one of the questions says: Why can a p-n junction connected in series with an n-p junction not act as an p-n-p transistor. My only thoughts were that the base element must be thin (approx 10 wavelengths of light) and in thus in this...

Hi I need circuit diagrams for studying P-N junction & Zener Diode under forward and reverse bias. I know they are available on Google, but I had a few questions, and if I understand the answers, I won't need circuit diagrams. 1. a) Some circuit diagrams have a rheostat connected in series...

Hello, I have read (wiki and physicsforums besides other sources) about how preparing an ohmic junction is hard on wafers in the clean room and that usually one gets a Schottky barrier instead, if one is not careful enough. This makes me wonder, how come that people used to get an ohmic...

I'm having trouble fully conceptualizing drift current- what I always hear is that it is caused by minority carriers within one diffusion length of the junction being swept across by the electric field that is generated by the imbalance caused by diffusion of electrons. Here is what I am...

For the network shown, show that the resistance Rab = (27/17)ohms . http://www.webassign.net/pse/p28-28.gif Figure P28.28 My attempt to the problem: I got the first following equations: I1-I3-I2=0 I4+I6-I1=0 I2+I5-I6=0 I3-I4-I5=0 Note that I3 and I4 are currents flowing at the top...

What are e and V in exponent of the equation I = I0(eeV/kT - 1)? is it really one variable "eV", as in electron volts, or is e just 2.718... and V for volts?

Hello all, I am somewhat confused in understanding the depletion region of a p-n junction diode.Everywhere a depletion region is defined as a region near the p-n junction which is devoid of charge carriers.And the formation of this region is said is explain that it is due to the diffusion of...