What is a Bridgman Furnace?

A Bridgman furnace is an industrial furnace used specifically for crystal growth. It uses a specific technique developed by Percy Williams Bridgman, a Harvard physicist. This blog post will discuss the method used in a Bridgman furnace and its applications.

The Bridgman Method

Within a Bridgman furnace, there is a distinct temperature gradient, and a crucible containing the pre-synthesized material is slowly transferred along the axis of this temperature gradient. As the material melts through the decreasing temperatures it forms a single crystal.

In a similar technique called the Stockbarger method, that’s name is often used interchangeably with the Bridgman Method, there are three distinct temperature zones within the furnace. The top zone has a temperature higher than the melting point, and the bottom zone has a temperature lower than the melting point. There is a middle zone that acts as a baffle between the two zones. This method is often used in a Bridgman furnace as it provides improved control over the temperature gradient.

The material in the crucible is completely melted in the hot zone of the Bridgman furnace and comes into contact with a single crystal seed at the bottom of the crucible. This crystal ensures that there is a single-crystal growth.

The crucible is then slowly transferred to the section of the furnace that has a temperature below the melting point, and it is in this section where the crystal growth starts. Once the entire crucible has been transferred through the cold section, the melt is converted into a solid single-crystalline ingot.

The Bridgman method is a popular choice for producing a range of semiconductor crystals, such as gallium arsenide, which can be difficult to develop using other methods.

Bridgman Furnaces from Thermcraft

In addition to the standard range of industrial furnaces Thermcraft develop and manufacture, they can also build custom furnaces to exact specifications, including Bridgman furnaces.

In the past Thermcraft have built completely custom, vertical Bridgman crystal growing furnace system for a client. This specific furnace was designed with geared stepper motors for complete control of the furnace rotation and sample transportation. It featured three zones and had a maximum temperature of 1200oC. A graphic user interface PLC control provided the client with complete control of the furnace, which provided them with ease of use.

Thermcraft have the knowledge and facilities to build Bridgman furnaces to exact specifications. If you require a Bridgman furnace but can’t find what you need on the market, please contact us, and one of our engineers will be happy to go over your options.

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