Surface contact type semiconductor diode, its PN junction is made by alloy process. The surface contact diode has a large PN junction area and can pass a relatively large current. It is generally used in low-frequency rectifier circuits.
It is a planar semiconductor diode, and its PN junction is made by a diffusion process. Planar diodes are commonly used as silicon planar switching tubes. When the PN junction area is large, it is suitable for high-power rectification; when the PN junction area is small, it is suitable for use as a switching tube in pulse digital circuits.
