The Chemistry of an LED

Introduction

I chose to do the chemistry of an LED, because I enjoy learning about electronics. LED’s affect the daily lives of everyone! They are in anything from TV screens, to car lights, and in home lighting. An LED or Light emitting diode is an electronic component that creates visible light when a current is applied. My life is affected by LED’s because I use LED’s at my business everyday, they are used to light my house. and they are in my Mac’s display. Composition of ...

    • Semi conductive chip
      • Indium gallium nitride (InGaN): blue, green and ultraviolet high-brightness LEDs
      • Aluminum gallium indium phosphide (AlGaInP): yellow, orange and red high-brightness LEDs
      • Aluminum gallium arsenide (AlGaAs): red and infrared LEDs
    • Clear shell around the LED
      • Plastic
    • Legs of the entire component
      • Copper tinned wire

Main Chemicals, Compounds, Components

LED Semiconductor

    • How? The LED is composed of a semiconductive wafer that is made in a large oven. Silicon is placed in the oven and metal impurities are stirred in so that there is a path for electrons to flow.These wafers are cut down into extremely small wafers that then have metal contacts connected to them. This is how the electricity is able to flow. Gold is then used to connect the two contacts that have the electricity supplied to them.
    • What? An LED
    • When? It was first discovered in 1907 but the ones used today were developed in 2006, but they are always changing
    • Why? LEDs have many great uses like the lights in a car or the pixels in a TV. It was created for portable light
    • Where? They are developed at many places by companies like Nichia and Samsung LED.

Liquid Plastic Mold

    • How? Plastic pellets are placed in a hopper. The plastic then falls into a heating chamber. When ready they are ready a screw the melted plastic into a mold of the desired shape and they are cooled.
    • What? The plastic mold that the LED is encased in. Plastic can be made from the elements carbon, hydrogen, oxygen, nitrogen, chlorine, and sulfur.
    • When? The well known plastic of today was created in 1907 by Leo Baekeland
    • Why? Plastic is pretty much used in everything in today’s society.
    • Where? Plastic is made by a wide variety of manufacturers

Chemistry's Role

The LED is composed of a semiconductive wafer that is made in a large oven. Silicon is placed in the oven and metal impurities are stirred in so that there is a path for electrons to flow.These wafers are cut down into extremely small wafers that then have metal contacts connected to them. This is how the electricity is able to flow. Gold is then used to connect the two contacts that have the electricity supplied to them. The LED semiconductor is not naturally occurring and is man-made.

The plastic comes from natural substances like coal or crude oil. Plastic is refined into pellets. Plastic pellets are placed in a hopper. The plastic then falls into a heating chamber. When ready screw pushes the melted plastic into a mold of the desired shape and it is cooled.

Background Research

    1. Englishman Henry Joseph discovers that inorganic material lights up when an electric current is applied (1907)
      1. Discovery is often forgotten
    2. Russian physicist Oleg Lossew observes what he called the “Round Effect” of light emission (1921)
    3. French Physicist Georges Destriau discovers light emission in zinc sulfate (1935)
      1. Calls it Lossew light in honor of Oleg
    4. First LED is introduced in 1962. It was the first LED with visible wavelength.
      1. Birth of industrially-produced LED
    5. New wavelengths are created
      1. The colors green orange and red are visible
    6. 1995 first LED with white light developed
    7. 2006 Household LEDs are introduced due to high efficiency

What is it? An LED or Light emitting diode is an electronic component that creates visible light when a current is applied.

What is it made of? Various chemical described below, plastic(the coating), the legs are made of tinned copper wire, and a semiconductor led chip.

What chemicals are in it?They are created of compound semiconductor materials, which are the elements from group 3 and 5 they are:

Indium gallium nitride (InGaN): blue, green and ultraviolet high-brightness LEDs

Aluminum gallium indium phosphide (AlGaInP): yellow, orange and red high-brightness LEDs

Aluminum gallium arsenide (AlGaAs): red and infrared LEDs

Gallium phosphide (GaP): yellow and green LEDs

What are the Chemical reactions needed? When electricity flows through the chemical causing the electrons to become excited and therefore glow.

Components: Plastic, tinned copper wire, and LED semiconductor chip

About the Author

Kyle Eaton is a senior at Billings Senior High. He enjoys spending time doing various activities such as rock climbing, ice climbing, skiing, fishing, backpacking, hunting, and math. He is part of the National Honors society and he owns his own business. He is planning to attend Montana State University to attain a degree in engineering.