What is depletion: Definition and 67 Discussions

Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events.
The main causes of ozone depletion and the ozone hole are manufactured chemicals, especially manufactured halocarbon refrigerants, solvents, propellants, and foam-blowing agents (chlorofluorocarbons (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS). These compounds are transported into the stratosphere by turbulent mixing after being emitted from the surface, mixing much faster than the molecules can settle. Once in the stratosphere, they release atoms from the halogen group through photodissociation, which catalyze the breakdown of ozone (O3) into oxygen (O2). Both types of ozone depletion were observed to increase as emissions of halocarbons increased.
Ozone depletion and the ozone hole have generated worldwide concern over increased cancer risks and other negative effects. The ozone layer prevents harmful wavelengths of ultraviolet (UVB) light from passing through the Earth's atmosphere. These wavelengths cause skin cancer, sunburn, permanent blindness, and cataracts, which were projected to increase dramatically as a result of thinning ozone, as well as harming plants and animals. These concerns led to the adoption of the Montreal Protocol in 1987, which bans the production of CFCs, halons, and other ozone-depleting chemicals. Currently, scientists plan to develop new refrigerants to replace older ones.The ban came into effect in 1989. Ozone levels stabilized by the mid-1990s and began to recover in the 2000s, as the shifting of the jet stream in the southern hemisphere towards the south pole has stopped and might even be reversing. Recovery is projected to continue over the next century, and the ozone hole is expected to reach pre-1980 levels by around 2075. In 2019, NASA reported that the ozone hole was the smallest ever since it was first discovered in 1982.The Montreal Protocol is considered the most successful international environmental agreement to date. Following the bans on ozone-depleting chemicals, the UN projects that under the current regulations the ozone layer will completely regenerate by 2045.

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  1. G

    MCNP6 BURN -- Testing about burnable poison depletion

    Hello, I'm testing about burnable poison depletion with mcnp6. I'm using m1 92233.82c -7.91619E-01 90232.82c -8.75802E-02 8016.82c -1.20800E-01 for fuel and m12 64152.82c -1.39023E-03 $ gd-152 64154.82c -1.53529E-02 $ gd-154...
  2. A

    Is there a program that can run depletion calculations in reverse?

    I was having a conversation with a coworker and this question came up: is there a program like ORIGEN (or maybe even ORIGEN) to run decay calculations in reverse? It's a relatively easy process to start with a given quantity of an isotope (e.g. U236), run it through a program such as ORIGEN...
  3. Mr_Allod

    Depletion width of linearly doped PN-junction

    Hello there, I have derived the expressions for electric field and potential to be the ones above, then for continuity at ##x = 0## I set the electric fields and potentials to be equal to yield the expressions: $$Sx_p^2 = Kx_n^2$$ $$V_{bi} = V_n - V_p = \frac {q}{3\epsilon} \left( Sx_p^3 +...
  4. Kaushik

    B How does the doping concentration affect the depletion width?

    I do not understand why that is the case. Is there any intuitive explanation for it? Thanks
  5. C

    Engineering Depletion region capacitance in MOSFET

    I would like to ask about the behavior of a MOSFET as a capacitor, particularly at the onset of inversion/weak inversion - see Fig 2.6(c) At this stage in Fig 2.6(c), there is positive charge at the gate metal/poly contact, then an insulator oxide and then negative ions (positive holes have...
  6. O

    Effect of doping concentration on the depletion width of p-n junction diodes

    My question for now is as follows: Why does a high doping concentration causes a decrease in the thickness of depletion region. Any help will be highly appreciated! Thanks a bunch Regards!
  7. C

    MCNP keff > 1.0 depletion question

    I am running some depletion calculations and have noticed odd behavior when keff is much greater or lower than one in the number of absorption's taking place on the outside the reactor. MCNP seems to be deleting the neutrons after it has reached the number of fissions required for the power...
  8. K

    B A couple of questions about diodes and the depletion region

    In a diode, we have N side, P side, and a depletion region, made of positive and negative charged sides. N side and P side of the diodes are neutral charge. In N side there are free electrons. In the positive charged side of the depletion region, there are positively ionized atoms that "lack"...
  9. G

    I Relationship between the depletion region and the band gap of a diode?

    Hi, Lately I've been reading about a lab exercise in which Planck's constant is estimated using LEDs. Every procedure I've encountered states that the energy of an emitted photon (and by extension the potential across the semiconductor's band gap) is equal to the threshold voltage multiplied by...
  10. Pushoam

    Effect of doping level on the width of the depletion layer

    Homework Statement Homework EquationsThe Attempt at a Solution I think before getting the steady state, after doping there are more electrons in n-region and there are more holes in p-region, so the more electrons go towards the p-region and more holes go toward the n - region. Consequently...
  11. S

    I Why isn't the depletion layer width equal in the p and n

    Hello, I've been researching photovoltaics and I've seen some articles which state that the width of the depletion layer is not equal on both sides on the pn junction. i don't understand why this occurs I've tried to research why and how this happens but have been unable to find an answer.
  12. A

    Effect of Doping on Depletion Region Width

    In an unbiased p-n junction, how does increase in doping affect the width of Depletion Region? I read somewhere that width decreases as increase in carrier concentration leads to more recombination of majority carriers with oppositely charged ions of their depletion regions leading to a...
  13. T

    B Existence of depletion layer in contact surface

    in a P-N junction diode, in an equilibrium state, a depletion layer forms in the surface of contact of N type and P type. But the problem is, this layer is formed by diffusion of electron to a lower electron density zone. Why does it always have to form right in the contactt surface? when...
  14. T

    B Forward Bias: Why does width of depletion layer decrease?

    The depletion layer is formed by the movement of electrons from the n to p side and holes from p to n side of the diode. The layer consists of positively charged donor ions close to the n side and negatively charged acceptor ions close to the p side. When in equilibrium,the barrier potential...
  15. A

    I Depletion region and Schottky Barriers

    I am having some trouble understanding the physics behind the formation of Schottky Barriers. According to the convential theory, the idea is that for an n-type semiconductor the electrons in the conduction band can lower their energy by filling empty states in the metal. This in turns creates a...
  16. C

    Why Does the Depletion Layer Affect Acceptor Atom Concentration in PN Junctions?

    Homework Statement I'm doing a course in solid state electronics and we just started PN junctions etc. I'm a bit confused. So here is what I know so far: Initially the P and N regions are separated by a a PN junction. At 300K as the acceptor atoms on the P side and donor atoms on the N side...
  17. H

    Solve Equation (1) to Get Equation (2): The Depletion Voltage & Electric Field

    The electric field ...(1) by saying that ...(2)I tried to integrate equation (1) from r2 to r1 but could not get equation(2). Any suggesting. Thanks
  18. G

    Depletion zone and current in forward-biased PN junction

    Hello. I've learned that in PN junction, forward-biasing on it pushes holes in P-type and electrons in N-type toward the junction so depletion width is reduced. Is it due to that in N-type side(P-type side), pushed electrons (holes) are recombined with holes (electrons) in depletion zone? And...
  19. G

    Depletion zone and current in forward-biased PN junction

    Hello. I've learned that in PN junction, forward-biasing pushes holes in P-type and electrons in N-type forward junctions so depletion width is reduced. Is it due to that in N-type (P-type), pushed electrons (holes) are recombined with holes (electrons) in depletion zone? And what is true...
  20. R

    Ozone Depletion: A Cause for Concern Despite Limited UV Radiation

    If only 14% of the total solar emission is in the UV region, why is ozone depletion a cause for concern. Considering that only a small fraction of the sun's total radiation reaches earth.
  21. T

    Derivation of width of depletion layer in the pn-junction

    Hello, I read a derivation for the width of the depletion region W in "SEMICONDUCTOR DEVICE FUNDAMENTALS" by Robert F. Pierret in which at one point it says: http://imageshack.com/i/ipbgKsK9p Here again for better readability: x_N = \sqrt{\frac{2 K_S...
  22. Y

    Depletion region vs Film thickness

    Here's something I can't get my head around: Take a diode (can be schottky, p-n etc) where the predicted depletion region is larger than the actual thickness of that layer will ever be. What happens? I've seen papers where its assumed that this curtails the built in potential. But it sounds...
  23. R

    Band bending, depletion layer thickness, density of occupie

    Homework Statement Consider an n-type Si (Eg =1.1eV, ED=EC, εr=11.8) with a bulk doping density ND=1×1017cm-3, a density of acceptor type surface state 1×1014 cm-2 and these states are at the middle of the band gap. Evaluate the amount of: a) band bending b)depletion layer thickness c) density...
  24. reddvoid

    Capacitances in NAND2 depletion mode nmos logic

    Why we are not writing Cgs Cdb in depletion mode nmos here why no Csb in bottom nmos Can somebody please explain how to write which components of Cload or provide some links from where i can understand it better thank you, this picture is from...
  25. P

    Depletion region in n-type ohmic contact

    Hello every one, Here in below figure we can see an ohmic contact formation between a metal and n-type semiconductor . Here how the N-type semiconductor bands are banded upward ? and what type of depletion charge exists there ?
  26. S

    MCNP Depletion Code -- Help please

    Hello, I am a graduate student attempting to run evaluate the depletion of a ceramic film attached to the moderator-side of the fuel clad. I am having some issues with my MCNP syntax/code and I was wondering if one could assist. My input file is attached. I am not looking for someone to...
  27. C

    A question on p-n junction depletion layer

    Hi, I'm studying the p-n junction and I'm a little confused about the depletion layer that forms. I understand how electrons and holes diffuse across the junction, recombine and leave charged ions but what I don't understand is why the ions remain fixed around the junction. Surely the...
  28. H

    Double Layer or Depletion Region?

    Hello everyone, Recently I have been studying double layers. As I have studied I have realized that there seem to be a lot of similarities between a double layer and a depletion region in a PN junction. The each form electric fields (and thus have a capacitance) and they each limit (or...
  29. A

    Is the P-N junction the only means to acheive a depletion region?

    Hi, I have a quick question. When constructing a semiconductor diode, the P-N junction is used to create a depletion region (depleted of mobile majority carriers) which is the active volume of the diode/detector. The region enables an electric current generated from the incomming radiation to...
  30. I

    Solid state depletion region

    how does letting the electrons diffuse to the P material/region lead to a "depletion" region in the center where the N and P material meet? please go into detail
  31. 1

    MOS-Capacitor: Investigating Depletion Region Neutralization

    Hello everyone, My question is about MOS-capacitor, We know that, If we place +ve gate voltage on p-MOS capacitor holes are repelled from semiconductor-oxide interface leaving behind negative charge due to ionized acceptor ions,This results in a depletion region. Now the question is, If we...
  32. I

    Depletion zone of a n-i junction

    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...
  33. A

    Please explain me - width of depletion layer varies

    please explain me -- width of depletion layer varies hey guys, i need to know how does width of depletion layer varies with various factors and i have mentioned all my queries below 1.first of all i want to know how does width of depletion layer increases with decrease in doping content??as...
  34. S

    Qualitative Understanding of MOSFET in Depletion

    Homework Statement No actual problem statement. I'm just having trouble understanding what is happening during the depletion and inversion stages. See the attached picture. During the depletion stage, what does it mean by "immobile acceptor ions?" Homework Equations None The...
  35. A

    Origin of the depletion region in a p-n junction

    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...
  36. E

    Specfic question about the formation of the depletion region in a pn junction

    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...
  37. V

    Why does the width of depletion region is small in highly doped diode?

    Dear, In Zener Diode, In highly Doped diode,the breakdown(Zener breakdown) occurs in small voltage.How? Thanks& Regards, Viswanathan.M
  38. azizlwl

    Depletion region- diode

    At depletion layer of p region, there more negative ions thus negatively charged region. Likewise at n region, it is positively charged. Then why in equivalent forward bias the diode behave as a battery of .7v with positive at depletion region of the p region where it is negatively charged?
  39. R

    Depletion region formation?

    How the depletion region act as capacitor? My view is that there are no charges because if formed of recombination of charges. so, there is no charge... So, how can it act like a capacitor? How the electric field is created in depletion region? It's confusing me a lot ...
  40. K

    Effect of Doping Levels on Width of Depletion Region

    Homework Statement The problem is what would be the effect on the width of the depletion region of an unbiased PN junction on the doping levels of the P and N sides Homework Equations This is a conceptual question. There is no equation involved. The Attempt at a Solution Increase...
  41. F

    Medical Ego Depletion and Decision Fatigue

    So I've become aware that the more "good" choices we make, the easier it is to make a "bad" choice, e.g. if you're on a diet for a couple of months, its very easy to slip and have a piece of chocolate cake, that sort of thing. Here's the wikipedia. http://en.wikipedia.org/wiki/Ego_depletion So...
  42. V

    Triton Depletion Code for SCALE: Solving Reactor Core Activity Issues

    Hi I'm wondering if anyone has experience working with the triton depletion code for SCALE? I'm having some issues when I'm trying to calculate the activity in radioisotope targets surrounding my reactor core.
  43. F

    Depletion Layers in pn junction

    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...
  44. S

    P-n junction & transistors: depletion zone

    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...
  45. A

    In diode why there is creation of depletion region?advanced thanks.

    in diode why there is creation of depletion region? advanced thanks.
  46. H

    Doubt on Depletion Layer Width in Biased pn-Jnction

    " Depletion Layer is the region in diode which consists of ions( formed due to formation of octet configuration )of p-type and n-type dopants" What happens to the ions present in the depletion layer when a diode is biased? why the depletion layer width changes??
  47. B

    What is the Depletion Region in NMOSFET Transistors?

    Hello, I am a bit confused about depletion region in NMOSFET transistor. It says here in my book, that when you increase Uds (drain source) above Ugs(gate source) that the current get higher. Ok, makes sense if nothing, from Ohms law. Simultaneously, the depletion region get smaller in...
  48. N

    Calculating Densities and Width of Depletion Region in Ge

    Homework Statement a. The densities of electrons and holes required for the Fermi levels in both the p- and n-type Ge to enter the bands. That is, in n-type Ge the Fermi level coincides with the bottom of the conduction band and for p-type Ge the Fermi level coincides with the top of the...
  49. B

    Understanding Doping & Depletion Zone Formation

    Can someone explain to me in detail formation of depletion zone and doping. I thought i understood this but it confused me when it came to this depletion zone. If u dope silicone with a substance with 3 valence electrons this forms a hole right? How does atom then behave? Does it polarize...