Silicon GPP (Glass Passivated Pellet) chips are a type of rectifier diode that uses a pellet of silicon semiconductor material to allow current to flow in only one direction. The chip is then coated with a layer of glass to protect it from environmental factors. GPP chips are commonly used in low voltage, high frequency applications such as power supplies and DC/DC converters. The glass coating helps to improve the reliability and stability of the chip, making it more suitable for use in harsh environments.