Chapter 2: Materials and Devices¶

Introduction¶

Materials and Devices is concerned with how semiconductor devices, such as transistors, diodes, and sensors work and how they are built. Introductory courses cover the physics and properties of electronic materials: semiconductors, metals and insulators, and how these materials are combined to form electronic devices. Higher level courses specialize in particular areas such as optoelectronics, semiconductor processing, magnetics, or sensors. In the undergraduate semiconductor fabrication laboratory, students learn to use semiconductor processing equipment in the clean room to fabricate and test their own diodes and transistors.

Section Overview¶

A resistor is a two-terminal component which resists current flow in a circuit. The resistor depends on the resistivity of the material, length and cross-sectional area. Resistance has a unit of Ohms Ω .

From boundless.com.

Objectives¶

• Resistance Basics
• Use the digital multimeter
• Graph data
• Potentiometers

Materials¶

• Digital Multimeter
• Conductive Paper
• KL-46z
• Femal-Fmale WIres

The Digital Multimeter¶

Digital multimeter (DMM) is a useful measurement tool. There are three settings in a typical DMM; Voltmeter measures potential difference (voltage), Ohmmeter measures resistance, and Ammeter measures current.

Using a Digital Multimeter¶

The Mutimemeter is used to measure diffreant electrical quantities, we are going to look at how we are going to use it the follwing video is a good resoirse that looks at measuring Current, Volatge and Resistince.

Condaitve Paper¶

In this section, different lengths and widths of conductive paper will be used to explore the resistance equation. Using scissors, cut the piece of paper provided as shown. Set the strip marked "Keep for Lab 3" aside, as it is needed for the next lab, where a variable resistor is used to make a mini piano circuit.

Length¶

Explore the relationship between resistance and length by using strips numbered 1, 2, and 3. In this test, resistivity and cross sectional area are constant and length is varied. Measure the resistance of each of these strips using a DMM.

ρ

Strip 1 Resistance = Strip 2 Resistance = Strip 3 Resistance =

Width¶

Explore the relationship between resistance and cross sectional area by using strips numbered 4, 5, and 6. Resistivity, length, and thickness are constant. The width portion of cross sectional area is varied. Measure the resistance using the digital multimeter. Hint: Set the rotary switch to "200k"

Thickness¶

Using strips 1, 5, and 7, explore the relationship between cross sectional area and resistance. Stack the strips of paper on top of each other to create resistors of different thicknesses. Measure the resistance by using a digital multimeter. Use the resistance equation to calculate the approximate thickness of the paper. Assume the resistivity constant $\rho = 2.68$ Resistance= Thinkness=

Variable Resistor/ KL-46z VDD and GND¶

In this section a variable resistor, also known as a potentiometer will be created using a strip of conductive paper. The potentiometer could be used as a variable resistor in the circuit or as a voltage divider. For this lab, the potentiometer will be used as a voltage divider. Common applications that use a potentiometer are a light dimmer switch, a power supply, and speaker volume. We will also use the VDD and GND Pins on the KL-46z Boreds.

1. Locate the GND and 3.3 Volts Pins on the above figure.
2. Using the paper clips and Female-Female wires make the folliwing stamtics(Ask TA's for help when needed)
3. .

Study Questions¶

Please type out your answers to the following questions. They will be turned in at the beginning of next lab.

• List 3 ways the resistance of a resistor can be decreased. \emph{(Hint: use the equation for resistance
• List several products that are engineered using materials and devices concepts. Also, explain how they are related to materials and devices.
• Find an OSU professor in the materials and devices track and describe one of their current research projects.

Challenge¶

The KL-46z has analog in pins and a Four Digit 7-seg Display,use that to make a volimeter use the next segment of code for Reference.

#include "mbed.h"
#include "SLCD.h"

SLCD slcd;
int n;
float c;
char buffer[50];
AnalogIn pot(PTB3);
int main() {
   
 slcd.Home();
   
while (1) {
    slcd.clear();
    slcd.Home(); 
    PwmOut led(LED_GREEN);
    c = (1000-(pot*1000))*0.0033; 
    led = 1;
    n = sprintf (buffer, "%.3f", c);
    slcd.clear();
    slcd.Home();  
    slcd.printf(buffer);     
    wait(0.4);    
        
        
        
    }
}