Pratique du Shadowing: What Is A Semiconductor? - Apprendre l'anglais à l'oral avec YouTube

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Science!
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Science!
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Here I have a circuit with a battery, light bulb, and gap.
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If I fill this gap with a metal, the light comes on.
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If I fill this gap with glass, the light stays on.
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You probably already know this because metal is an electric conductor and glass is an insulator.
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But what happens when I fill this gap with a silicon wafer? wafer.
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The light stays off so you might think the silicon is an insulator but what if I heat it up?
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Thank you.
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It lights up.
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The silicon is insulating at room temperature but conducts electricity when it's very hot.
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It's a semiconductor, whose conductivity changes based on the environment.
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This special ability makes semiconductors the perfect brains for electronic devices.
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Circuits of small semiconductor switches,
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called transistors, are at the heart of computer chips and enable them to do math and run programs.
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Semiconductors have enabled electronics to become smaller, faster, and more reliable.
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But what is it exactly about these semiconductors that allow them to either conduct or insulate?
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In a single atom, electrons can occupy specific energy levels.
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When multiple atoms bond, the electrons are shared between them.
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But because the atoms are now interacting,
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the energy levels shift around.
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In a solid, trillions and trillions of atoms interact with each other.
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Their individual energy levels smear into energy bands.
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For a material to conduct,
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the electrons must be able to jump from lower energy states to higher ones.
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The spacing of these energy levels and how they're filled with electrons determines if if the material is a conductor,
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insulator, or semiconductor.
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If there's a huge gap between the lower energy levels and the higher ones,
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it's hard for electrons to jump to the higher ones,
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so current can't flow, and it's an insulator like this glass.
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Metals have no gap at all.
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Electrons can move to the higher energy levels with no problem.
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Current can flow.
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Semiconductors fall somewhere in the middle.
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They have a medium-sized band gap.
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So technically, I can make this glass conduct electricity
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if I added enough energy through heat to push the electrons into a higher band.
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But that amount of heat would either melt or break the glass before it actually conducts.
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This is true of most insulators.
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The amount of energy needed to make them conduct is just too high.
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But in a semiconductor, the band gap is small enough
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that electrons can jump into the higher energy band so that current can flow.
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The amount of heat we apply determines how many electrons jump into the higher band and how much current flows.
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And heat isn't the only way to change the conductivity in a semiconductor.
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We can also use light,
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electric currents, and in a computer, electric fields.
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As I've said, computers are made up of semiconductor switches called transistors that switch between conducting and insulating.
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Computers use electric fields because heat is slow and would burn too much energy.
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We can turn this wafer into a computer chip by printing a circuit of transistors on it using a process called photolithography.
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Here, in the photo room,
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we cover the wafer with a light-sensitive material and expose it to light that we shine through a pattern mask.
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Then, we develop the wafer,
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like film and photography, which leaves behind a pattern that becomes the circuit.
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Printing the transistors at once lets you make circuits that are smaller and cheaper than if you built them from individual parts.
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Transistors make up the logic elements,
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the memory components, and the communication modules that let computers talk to each other.
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With semiconductors, you can cheaply add transistors to almost any device you can think of,
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from spaceships to servers to maybe even your toaster.
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Semiconductors have enabled the technological revolution,
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the internet, the computer, and the cell phone.
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No semiconductors, no information age.
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I'm Jamie and thanks for watching this episode of Science Out Loud.
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Be sure to check out some of our other videos,
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including mine, on how computers compute.
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Check out our website for more information.
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The end is...
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I'm just like...

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About This Lesson

In this lesson, learners will explore the concept of semiconductors through an engaging video transcript. By focusing on the technical details and practical implications of semiconductors in electronics, learners will enhance their vocabulary and comprehension skills. Through repetition and practice, you will improve your English pronunciation and speech fluency by shadowing the speaker's tone and pace. This is especially beneficial for understanding scientific terminology and intricate explanations.

Key Vocabulary & Phrases

  • Semiconductor - a material that can conduct electricity under certain conditions.
  • Insulator - a material that does not conduct electricity.
  • Conductivity - the ability of a material to conduct electricity.
  • Transistor - a semiconductor device used to amplify or switch electronic signals.
  • Band gap - the energy difference that determines whether a material is a conductor, insulator, or semiconductor.
  • Photolithography - a process used to create patterns on semiconductor wafers.
  • Energy levels - the specific energies that electrons can have in an atom.
  • Electron - a subatomic particle with a negative charge that plays a crucial role in electricity.

Practice Tips

To make the most of this lesson, consider using a shadowing app or site that allows you to practice alongside the video transcript. The speed of the speaker requires careful listening and repetition. Here are some tips to guide you:

  • Start Slow: Begin by playing sections of the video at a slower speed. Focus on mimicking the speaker's pronunciation and intonation.
  • Repeat Frequently: Repeat phrases and sections multiple times until you feel comfortable with the vocabulary and the flow of speech.
  • Use Shadow Speech: Engage in shadow speech by speaking simultaneously with the video. This technique will help you improve your speaking fluency and confidence.
  • Check Your Progress: Record yourself as you practice. Listening to your recordings will help you identify areas for improvement, such as pronunciation or pacing.
  • Focus on Key Phrases: Pay special attention to key vocabulary, as mastering these terms will enhance your understanding and ability to discuss related topics.

By employing these shadowing techniques, you are likely to improve your English pronunciation significantly while deepening your understanding of semiconductors and their role in modern technology. Embrace the process, and enjoy your learning journey!

Qu'est-ce que la technique du Shadowing ?

Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.

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