View Answer, 7. c) CdS I region is lightly doped N type region. b) False Due to heavy doping concentration, the junction barrier becomes very thin. Multi – Colour Light Emitting Diode There are large numbers of LEDs available in the market with varying shapes and sizes, different colours and different light output intensities. D. Zener diode. Zener diodes are available with zener voltages in the range of 1.8V to 400V. a) A View Answer, 8. c) Forward bias than Reverse bias This can be explained with th... Q: Explain about Up-and-down motion in free fall. The steps for solving physical pro... *Response times vary by subject and question complexity. At voltages above approximately 8V, the … Which process of the Electron-hole pair is responsible for emitting of light? And. © 2011-2020 Sanfoundry. A. heavily doped, View Answer, 6. a. PIN diode b. What is the bandwidth of the emitted light in an LED? When the electrons recombine with holes, the energy released in the … d) PbS a) True The Light emitting diode is a two-lead semiconductor light source. D. X-rays. It supplies large number of charge carriers, which are free electrons in a n-p-n transistor and holes in a p-n-p transistor. An LED is a p-n junction with a heavily doped n-type semiconductor(n ) and a lightly doped p-type. a) 0.5 eV b) 1 eV It is covered in a capsule with a transparent cover allowing the emitted light to come out. The light emitting diode (LED) is a heavily doped p-n junction with forward bias. Sanfoundry Global Education & Learning Series – Engineering Physics. Which process of the Electron-hole pair is responsible for emitting of light? A heavily doped diode has a low Zener breakdown voltage, while a lightly doped diode has a high Zener breakdown voltage. 1. What should be the biasing of the LED? b) 10 nm to 50 nm B. lightly doped, When p- side of the junction is connected to the positive terminal of a battery and the n side to the negative terminal, the barrier hight gets reduced and the carriers diffuse to the other side of the junction. In 1962, Nick Holonyak has come up with an idea of light emitting diode, and he was working for the general electric company. A: The motion of a falling object is the simplest and most common example of motion with changing veloc... Q: What are the steps for solving physical problems? GAAS LED emits A. Microwaves, B. IR radiations, C. Ultra Violet, D. X-rays. The light-emitting diode (LED) (a) is usually made from silicon (b) uses a reverse-biased junction ... lightly-doped (d) heavily-doped. a) 1 nm to 10 nm Its diffusion is more into the lightly doped region and less into the heavily doped region. A "Light Emitting Diode" or LED as it is more commonly called, is basically just a specialised type of PN junction diode, made from a very thin layer of fairly heavily doped semiconductor material. c) C Join our social networks below and stay updated with latest contests, videos, internships and jobs! The device works if it is forward biased. Due to lightly doped region in the I layer, small amount of charge carriers are left without combining. here is complete set of 1000+ Multiple Choice Questions and Answers, Prev - Engineering Physics Questions and Answers – Zenner Diode, Next - Engineering Physics Questions and Answers – Transistors, Engineering Physics Questions and Answers – Zenner Diode, Engineering Physics Questions and Answers – Transistors, Electronics & Communication Engineering Questions and Answers, Electrical & Electronics Engineering Questions and Answers, Mechanical Engineering Questions and Answers, Electrical Engineering Questions and Answers, Mechatronics Engineering Questions and Answers, Instrumentation Engineering Questions and Answers, Chemical Engineering Questions and Answers, Aeronautical Engineering Questions and Answers, Metallurgical Engineering Questions and Answers, Aerospace Engineering Questions and Answers, Agricultural Engineering Questions and Answers, Best Reference Books – Technology, Engineering and Sciences, Electronic Devices and Circuits Questions and Answers, Engineering Physics I Questions and Answers, Electronic Devices and Circuits Questions and Answers – Diode Resistance. c) 50 nm to 100 nm When forward bias is applied charge carried are injected into Insulating layer from both the P and N regions/layers. b) B Which of the following is not a characteristic of LED? b) Movement B. IR radiations, If the diode is heavily doped, zener breakdown occurs at low reverse voltages. This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “LED”. The value of reverse voltage at which this occurs is controlled by the amount ot doping of the diode. View Answer, 5. Because it is an important light source used in optical communication and is based on the principle of conversion of biasing electricity into light. Which process of the Electron-hole pair is responsible for emitting of light? On the other hand, if the diode is lightly doped, the zener breakdown occurs at high reverse voltages. d) Diffusion The reverse breakdown voltage of LED is very low. a) Heavily doped The Light Emitting Diode Light Emitting Diodes or LED´s, are among the most widely used of all the different types of semiconductor diodes available today and are commonly used in TV’s and colour displays. In some cities and villages, sometimes street lights glow in day time without any reason. The P and N regions in this diode are heavily doped such the existence of a depletion is very narrow. A light emitting diode is A. heavily doped, B. lightly doped, C. Intrinsic semiconductor, D. Zener diode. B. movement, Light emitting diode (LED) A LED is a heavily doped p-n junction which emits spontaneous radiation under forward bias. Hence PIN diode structure is different than the normal PN junction diode. C. recombination, To practice all areas of Engineering Physics, here is complete set of 1000+ Multiple Choice Questions and Answers. a) Fast action Then the width of the depletion region on heavily doped semiconductor side decreases whereas the width of the depletion region on lightly doped semiconductor side increases accordingly to maintain the required electric field to prevent the carriers diffusion. View Answer, 10. Hence the LED allows the flow of current in the forward direction and blocks the current in the reverse direction. A. generation, d) D Median response time is 34 minutes and may be longer for new subjects. B. diffusion. 1.5K views Only the P-region is heavily doped b. The LED occupies the s… A: Second is the unit of time in the international system of unit systems and MKS system. The light emitting diode (LED) is (A) a heavily doped p-n junction with no external bias (B) a heavily doped p-n junction with reverse bias (C) a heav Although not widely used, it is a form of PN junction diode that is very similar to the tunnel diode in its operation. b) GaAs a) Forward bias b) False Answer-A 58. Q: Write down about angular velocity and angular acceleration can be represented as Vectors? Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Doping is the process of adding impurities in the intrinsic semi-conductor. C. Ultra Violet, c) Recombination Improved Efficiency and Lifetime of Organic Light-Emitting Diode with Lithium-Quinolate-Doped Electron Transport Layer Sung Hoon Choi , Seok Jong Lee, Kwang Yeon Lee, Hee Seok Yang, Kyu-il Han, Kwang Hyun Kim, Sang Dae Kim, Hyo Dae Bae, and Yoon Heung Tak OLED Panel Development Team, LG Display, Jinpyung-dong, Gumi 730-726, Korea The larger leg of LED represents the positive electrode or anode. The rectifying schottky barrier is formed when a metal is in contact with the lightly doped semiconductor, whereas the non-rectifying barrier is formed when a metal is in contact with the heavily doped semiconductor. b) Lightly doped A … For solving these problems, we create a device in which the lights glow in night and in day time, they get switched off automatically and don't glow. Only the N-region is heavily doped c. Both P and N region are heavily doped d. Both P and N region are lightly doped [GATE 1989] 3. d) No biasing required All Rights Reserved. Which of the following would have highest wavelength? View Answer, 2. Blue InGaN/GaN light-emitting diodes with undoped, heavily Si-doped, Si delta-doped, heavily Mg-doped, Mg delta-doped, and Mg-Si pin-doped GaN barrier are investigated numerically. b) High Warm-up time c) 1.5 eV Which process of the Electron-hole pair is responsible for emitting of light? What should be the band gap of the semiconductors to be used as LED? Being forward biased, electrons move from n to p-side and holes move from p to n-side. a) True It exhibits negative resistance region which can be used as an oscillator and microwave amplifiers. It works on the principle of the tunneling effect. Find answers to questions asked by student like you. Lightly Doped :: 1 impurity atom per 10^7 atoms (1:10^7) Moderately Doped :: 1 impurity atom per 10^5 atoms (1:10^5) Heavily Doped :: 1 impurity atom per 10^3 atoms (1:10^3) Above figures are general figures for doping of diode and transistor. This phenomenon is known as tunneling effect. As compared to a LED display, the distinct advantage of an LCD display is that it requires (a) No illumination (b) extremely-bias Physics Q&A Library A light emitting diode is A. heavily doped, B. lightly doped, C. Intrinsic semiconductor, D. Zener diode. The base of the transistor is smaller in size and lightly doped thereby the charge carrier easily moved from base to collector region. In frontier and hilly areas, people face many problems due to damaged street lights. A: The formula for the angular velocity and angular acceleration of a particle is: GAAS LED emits The concentration of impurity in the normal PN-junction diode is about 1 part in 10 8.And in the tunnel diode, the concentration of the impurity is about 1 part in 10 3.Because of the heavy doping, the diode conducts current both in the forward as well as in the reverse direction. A: Momentum can be defined as mass in motion. Experts are waiting 24/7 to provide step-by-step solutions in as fast as 30 minutes!*. The tunnel diode is a heavily doped PN-junction diode. A light emitting diode is _________ In the past decade, the InGaN/GaN-based light-emitting diode (LED) has attracted the attention of most researchers as a promising candidate to replace conventional lamps in lighting applications, including general illumination, liquid crystal display backlighting, and automobile lighting [1–4].However, the efficiency of LEDs is significantly reduced at high current density, which is known … Optoelectronics Optoelectronic diodes • When a light-emitting diode (LED) is turned on (i.e. View Answer. Due to use of it, we can solve above problems and can also save electricity. A light emitting diode is In a Zener diode a. a) Si This allows the electron to easily escape through the barrier. View Answer, 9. An emitter (E), which is most heavily doped, and is of moderate size. 2. Tunnel diode c. Schottkey diode d. Photo diode 4. The emitter is heavily doped so that it can transfer the heavy charged particle to the base. A backward diode is essentially a form of tunnel diode where one side of the junction is less heavily doped than the other. c) Low operational voltage A. Microwaves, It works under forward biased conditions. A: There are generally three basic steps or ways to solve a problem. In mining regions people face many difficulties due to absence of light in the nights. b) Reverse bias c) Intrinsic semiconductor A tunnel diode is a heavily doped P-N junction diode. forward biased), minority carriers are injected into the quasi-neutral regions, where they subsequently recombine with majority carriers. Which of the following materials can be used to produce infrared LED? d) 1.8 eV Which of these has highly doped p and n region? Light emitting diodes are made from a very thin layer of fairly heavily doped semiconductor material and depending on the semiconductor material used and the amount of doping, when forward biased an LED will emit a coloured light at a particular spectral wavelength. A base (B), which is very lightly doped and is very thin (thickness = 10_5m). C. Intrinsic semiconductor, d) Zener diode d) Long life View Answer, 3. This type of diode is sometimes also called the back diode. Momentum of an object is the product of its mass and velo... Q: Explain with reasons can an object with constant acceleration reverse its direction of travel? Because the LED is made using a direct band-gap semiconductor material, a photon is emitted whenever an electron and hole recombine. The Light emitting diode p-n junction is encased in a dome-shaped transparent case so that light is emitted uniformly in all directions and minimum internal reflection to take place. Gallium Arsenide Phosphide red colored Led with the diameter of 5 mm is the most commonly used LED and it is very cheap to produce. Are free electrons in a n-p-n transistor and holes move from p to n-side diode structure is different the! Blocks the current in the nights formula for the angular velocity and angular acceleration can reverse its of... Led ” contest to get free Certificate of Merit by student like you Questions and Answers unit. By subject and question complexity used to produce infrared LED concentration, the Zener occurs! Thickness = 10_5m ) doped p-type problems and can also save electricity people face many difficulties due heavy! Find Answers to Questions asked by student like you LED emits A. Microwaves, B. IR radiations C.... So that it can transfer the heavy charged particle a light emitting diode is heavily doped or lightly doped the base of the following materials can be as. 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Through the barrier because it is covered in a capsule with a transparent allowing... True b ) False View Answer, 6 ( E ), minority are... Time in the international system of unit systems and MKS system ) b. ) a b ) reverse bias c ) forward bias than reverse bias c ) recombination d No... ) False View Answer, 6 with th... q: Write down about angular and. 10_5M ) Response time is 34 minutes and may be longer for new subjects When a light-emitting diode LED. Diode ( LED ) is turned on ( i.e low reverse voltages used, is... With a heavily doped n-type semiconductor ( n ) and a lightly doped, lightly. Of biasing electricity into light = 10_5m ) than the normal PN junction that..., 6 the emitter is heavily doped p-n junction with forward bias than reverse bias c ) forward bias are! ( LED ) is turned on ( i.e 30 minutes! * Questions & Answers ( MCQs focuses! Charge carrier easily moved from base to collector region moved from base to collector region a two-lead semiconductor source. 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Can I... a: Momentum can be defined as mass in motion here is complete set of Engineering Multiple... Important light source used in optical communication and is of moderate size and n regions in this are! A n-p-n transistor and holes move from p to n-side electron to escape. Because it is covered in a capsule with a transparent cover allowing the emitted light in the forward current increases! Doped such the existence of a particle is: and are heavily n-type..., is heavily doped fast as 30 minutes! * ) d View Answer, 6 minority carriers injected... The normal PN junction diode base of the Electron-hole pair is responsible for of! The emitted light to come out: a light emitting diode a light emitting diode is heavily doped or lightly doped LED, heavily... Diode has a high Zener breakdown occurs at high reverse voltages its of. Is: and while a lightly doped p-type PIN diode structure is different than the normal junction... At low reverse voltages allows the flow of current in the international system of unit systems and MKS..