PHY_10_50_V2_LP_Semicon.devices

Long-term plan unit: Current in different medium

School:

Date:

Teacher name:

Grade: 10

Number present:

absent:

Theme of the lesson

Semiconductor devices

Learning objectives that are achieved at this lesson(Subject Program reference)

10.4.3.3 - describe the electric current in semiconductors and explain the use of semiconductor devices;

Lesson objectives

•     To describe temperature dependence of a thermistor and its application;

•     To give an example of  a photo resistor;

•     To know the principle of semiconductor device;

•     List applications of a diode and a transistor;

•     To distinguish the circuit symbol of a thermistor, photo resistor, diode and a transistor;

Assessment criteria

Students can

•     describe temperature dependence of a thermistor and its application;

•     give an example of  a photo resistor;

•     explain the principle of semiconductor device;

•     List applications of a diode and a transistor;

•     distinguish the circuit symbol of a thermistor, photo resistor, diode and a transistor;

Language objectives

Values instilled at the lesson

Safety, Consideration to others, Co-operation, Opportunity for Life-Long Learning, Academic Integrity and Transparency, Respect for Self and Others

Cross-curricular links

Other subject links include Mathematics, IT

ICT skills

ICT links to use of computers, data loggers, scientific calculators and tablets etc. Making use of internet resources and encourage students to research information online as well as using ICT tools like professional presenter, use of smart board to aid learning.

Previous learning

Electric current in metals

Course of the lesson

Planned stages of the lesson

Planned activities at the lesson

Resources

Beginning of the lesson

7 min

Introduce students with the topic of the lesson and LO.

Starter activity 1: Matching

Work in pairs

Students do a task about semiconductors and revise the topic of previous lesson:

Students discuss answers and teacher might ask questions.. Aim of this activity to revise what they have learn and focus their attention to the new topic.

Slides

Video clip

Smartboard

Middle

20 min

10 min

 Teacher divides students into 4 groups. They will be provided with a theoretical material about their topics. Groups will be provided with the hangouts and do the reading task: 

Students’ task is to investigate different semiconducting devices and make a poster presentation.

1Group: Thermistors and its applications;

2 Group: Photo resistors and its applications;

3 Group: Semiconductor diodes and its applications;

4 Group: Transistors and its applications;

 Students will be given a 20 minutes to get prepared.

When groups are ready they present their posters and teacher might complete their answer, and ask questions.

First groups posters should include next information:

THERMISTOR

This is a type of resistor is made from a sintered semiconductor material which has a resistance that changes with temperature. There are two types of thermistor:
(i) negative temperature coefficient (NTC) – the resistance of the thermistor falls with increasing temperature 
(ii) positive temperature coefficient (PTC) - the resistance of the thermistor rises with increasing temperature 
The NTC is the type most often used in schools so I will just consider that type in detail.
The increasing temperature produces more free electrons and so the resistance falls. These electrons are able to 'jump' from the valence band to the conduction band. This increase in conduction electrons masks the effect due to the increase thermal motion of the atoms and electrons.

Uses of thermistors (NTC)

Thermistors are used as temperature sensors in thermostats in ovens and irons, in fire alarms and on the wing of a plane to detect when the temperature falls low enough for ice to form. They are also in use in premature baby units to detect when a baby may have stopped breathing, current limiting devices and thermometers.
During poster presentations other groups students make notes on their copybooks and ask any questions.

Second groups posters which will be about photo resistor should include next information:

 THE LIGHT EMITTING DIODE (LED)

The LED is likely to be the most important advance in lighting in the early part of the twenty first century. LEDs used to be available as low power indicators in two types – one that emitted red light and the other that emitted green light.

The big advance was the development of relatively high power LEDs that emitted white light. I have a torch that contains five LEDs that gives a total output of 15000 mcd (power consumption 0.6W) using a current of 150 mA at between 3 and 3.5V.

To understand how the LED works it is important to understand the workings of the semiconductor diode It is very likely that all homes will eventually be lit by LED light sources. They consume low power, are small, fairly robust, emit virtually no heat energy and give a good clear white light. Just like a normal semiconductor diode current flows when electrons move from the conduction band in the n type cathode" to the valance level in the p type "anode". The difference is that with the LED when the electron falls into a positive whole energy is released in the form of a photon. The wavelength of this photon depends on the energy gap of the materials of the p-n junction. White light emitting LEDs can be made in a variety of ways. One is to coat a blue emitting LED with a material that converts some of the blue light to yellow. The yellow light stimulates both the red and green receptors in the eye. When this yellow light is combining the original blue emitted by the LED the resulting output gives the impression of white light.

Third groups posters which will be about diodes should include next information:

THE SEMI-CONDUCTOR DIODE

The p-n junction

If a region of p-type material and a region of n-type material are formed side by side in a piece of silicon, a p-n junction is formed. It is important that this is made in one piece of the material so that the crystal lattice extends across the boundary. It is not sufficient just to have two pieces in contact.
Both the p-type and the n-type material are electrically neutral, but they both contain an imbalance of conduction electrons or holes. At the boundary, holes drift from the p-type towards the n-type material and electrons drift from the n-type to the p-type to reduce this imbalance. This diffusion of holes and electrons across the boundary sets up a potential barrier which prevents further change, the p-type region becoming slightly negative and the n-type becoming slightly positive. The barrier has a potential difference across it of about 0.1 V, although the exact size of the potential barrier depends on the material. These effects only occur over a very small region (about 10^-3 mm on either side of the boundary) known as the depletion layer

In order to check student understanding teacher offers a FA task which students will do individually:

At the end of the lesson teacher goes back to the LO and ask student complete the assessment  criteria table:

Ppt

Video clip

Worksheets

Handout presentation

End

2 mins

Reflection

Today I found out  ...

It was interesting …

It was difficult…

I understand that…

Notes.

Differentiation – how do you plan to give more support? How do you plan to challenge the more able learners?

Assessment – how are you planning to check students’ learning?

Health and safety regulations

During watching video teacher might ask more able learners conceptual questions so it help others understand more

By observing their reflection and answers

All safety rules confirmed

Reflection

Were the lesson objectives/learning objectives realistic? Did all learners achieve the LO?

If not, why?

Did my planned differentiation work well?

Did I stick to timings?

What changes did I make from my plan and why?

Use the space below to reflect on your lesson. Answer the most relevant questions from the box on the left about your lesson. 

Summary evaluation

What two things went really well (consider both teaching and learning)?

1:

2:

What two things would have improved the lesson (consider both teaching and learning)?

1:

2:

What have I learned from this lesson about the class orachievements/difficulties of individuals that will inform my next lesson?