A low noise device includes an isolation feature in a substrate. The low noise device further includes a gate stack over a channel in the substrate. The gate stack includes a gate dielectric layer extending over a portion of the isolation feature, and a gate electrode over the gate dielectric layer. The low noise device further includes a charge trapping reducing structure adjacent to the isolation feature. The charge trapping reducing structure is configured to reduce a number of charge carriers adjacent an interface between the isolation feature and the channel.