A semiconductor pixel unit (120; 220; 320; 420; 800; 1200; 1700) adapted for sensing near-infrared light, the semiconductor pixel unit comprising: a single semiconductor substrate comprising a first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) arranged on top of a second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) electrically separated from the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) by means of an insulating region (102; 202; 302; 402; 802; 1202; 1702); means for generating a lateral electrical field (Edrift) in a region (103; 203; 303; 403; 803; 1203; 1703) underneath the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701), the electrical field (Edrift) being adapted for promoting transport of photoelectrons generated in the second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) by the near-infrared light after passing through the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) and through the insulating region (102; 202; 302; 402; 802; 1202; 1702); the second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) comprising at least one near infrared light detector (105a, 105b; 205; 305a, 305b; 405a, 405b; 805a, 805b; 1205a, 1205b; 1705a, 1705b) located at the surface of the semiconductor substrate for detecting the photoelectrons generated in the second semiconductor region by the near infrared light; characterized in that - the insulating region (102; 202; 302; 402; 802; 1202; 1702) between the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) and the second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) comprises a buried oxide layer (102; 202; 302; 402; 802; 1202; 1702). a single semiconductor substrate comprising a first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) arranged on top of a second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) electrically separated from the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) by means of an insulating region (102; 202; 302; 402; 802; 1202; 1702); means for generating a lateral electrical field (Edrift) in a region (103; 203; 303; 403; 803; 1203; 1703) underneath the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701), the electrical field (Edrift) being adapted for promoting transport of photoelectrons generated in the second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) by the near-infrared light after passing through the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) and through the insulating region (102; 202; 302; 402; 802; 1202; 1702); the second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) comprising at least one near infrared light detector (105a, 105b; 205; 305a, 305b; 405a, 405b; 805a, 805b; 1205a, 1205b; 1705a, 1705b) located at the surface of the semiconductor substrate for detecting the photoelectrons generated in the second semiconductor region by the near infrared light; characterized in that - the insulating region (102; 202; 302; 402; 802; 1202; 1702) between the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) and the second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) comprises a buried oxide layer (102; 202; 302; 402; 802; 1202; 1702). - the insulating region (102; 202; 302; 402; 802; 1202; 1702) between the first semiconductor region (101; 201; 301; 401; 801; 1201; 1701) and the second semiconductor region (104; 204; 304; 404; 804; 1204; 1704) comprises a buried oxide layer (102; 202; 302; 402; 802; 1202; 1702).