Date：2025-08-15 Categories：Product knowledge Hits：101 From：Guangdong Youfeng Microelectronics Co., Ltd
Semiconductor diodes and their characteristics
Semiconductor diodes can be divided into two types based on their structure and manufacturing process: point contact type and surface contact type.
A point contact diode is formed by installing a contact pin made of tungsten or gold wire on the surface of a P-type silicon crystal or N-type germanium crystal, making contact with the crystal surface, and then applying current treatment to form a layer of irregular crystal at the contact point of the contact pin. Depending on the type of metal wire used, they are respectively called tungsten bond diodes and gold bond diodes. The domestically produced 2APl-7 and 2APll-17 semiconductor diodes belong to this category. But the former is made of tungsten wire, while the latter is made of gold wire.
Most surface contact diodes are made by alloy method. Place a piece of indium on the surface of an N-type germanium crystal, and then melt a portion of germanium into the indium at high temperature. Then the temperature is lowered to allow the germanium melted in the rock to precipitate again, forming P-type crystals. This P-type crystal forms a P-N junction with the unmelted N-type crystal.
Point contact semiconductor diodes have a small contact area, resulting in a small capacitance between the contact pin and the barrier layer (about 1 microfarad); The inter electrode capacitance of surface contact diodes is relatively large, about 15-20 picocells. Therefore, the former is suitable for working in high-frequency situations, while the latter is only suitable for working in places with frequencies below 50 kHz; In addition, the former allows a small current to pass through and is suitable for detection in wireless equipment, while the latter can pass a larger current and is mostly used for rectification.
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