Extrinsic Photoresistor vs. Intrinsic Photoresistor

Attribute	Extrinsic Photoresistor	Intrinsic Photoresistor
Doping	Doped with impurities	No intentional doping
Conductivity	Higher conductivity	Lower conductivity
Response time	Slower response time	Faster response time
Temperature sensitivity	Less temperature sensitive	More temperature sensitive

Introduction

Photoresistors are light-sensitive resistors that change their resistance based on the amount of light they are exposed to. There are two main types of photoresistors: extrinsic and intrinsic. Extrinsic photoresistors are doped with impurities to enhance their light sensitivity, while intrinsic photoresistors are made of pure semiconductor materials. In this article, we will compare the attributes of extrinsic and intrinsic photoresistors to understand their differences and applications.

Extrinsic Photoresistors

Extrinsic photoresistors are made by doping a semiconductor material with impurities to increase their light sensitivity. The most common dopants used in extrinsic photoresistors are arsenic, antimony, and phosphorus. These impurities create additional energy levels in the semiconductor material, allowing it to absorb more light and change its resistance accordingly. Extrinsic photoresistors are typically more sensitive to light than intrinsic photoresistors, making them ideal for applications where high sensitivity is required.

• Enhanced light sensitivity
• Doped with impurities
• Additional energy levels
• Ideal for high sensitivity applications

Intrinsic Photoresistors

Intrinsic photoresistors are made of pure semiconductor materials without any impurities. This makes them less sensitive to light compared to extrinsic photoresistors. However, intrinsic photoresistors have a more predictable and stable response to light, making them suitable for applications where consistency is key. Intrinsic photoresistors are commonly used in light meters, cameras, and other devices where precise light measurement is required.

• Less sensitive to light
• Made of pure semiconductor materials
• Predictable and stable response
• Suitable for applications requiring consistency

Comparison

When comparing extrinsic and intrinsic photoresistors, it is important to consider the specific requirements of the application. Extrinsic photoresistors are ideal for applications where high sensitivity to light is needed, such as in light sensors for automatic lighting systems. On the other hand, intrinsic photoresistors are better suited for applications where consistency and stability are more important, such as in photography equipment.

• Extrinsic photoresistors are more sensitive to light
• Intrinsic photoresistors have a more stable response
• Extrinsic photoresistors are doped with impurities
• Intrinsic photoresistors are made of pure semiconductor materials

Applications

Extrinsic photoresistors are commonly used in light sensors, light meters, and other devices where high sensitivity to light is required. Their enhanced light sensitivity makes them ideal for applications where detecting small changes in light intensity is crucial. Intrinsic photoresistors, on the other hand, are used in photography equipment, solar panels, and other devices where consistent and stable light measurement is essential.

• Extrinsic photoresistors: light sensors, light meters
• Intrinsic photoresistors: photography equipment, solar panels

Conclusion

In conclusion, extrinsic and intrinsic photoresistors have distinct attributes that make them suitable for different applications. Extrinsic photoresistors are more sensitive to light due to the impurities added during manufacturing, while intrinsic photoresistors offer a more stable and predictable response to light. Understanding the differences between these two types of photoresistors is essential for selecting the right component for a specific application.