An optical sensing apparatus is provided. The optical sensing apparatus includes a substrate, one or more pixels supported by the substrate, where each of the one or more pixels includes an absorption region, a field control region, a first contact region, a second contact region and a carrier confining region. The field control region and the first contact region are doped with a dopant of a first conductivity type. The second contact region is doped with a dopant of a second conductivity type. The carrier confining region includes a first barrier region and a channel region, where the first barrier region is doped with a dopant of the second conductivity type and has a first peak doping concentration, and where the channel region is intrinsic or doped with a dopant of the second conductivity type and has a second peak doping concentration lower than the first peak doping concentration.