Amorphous silicon photosensor with oxygen doped layer

A photosensor comprising:

• a pair of first and second electrodes, said first electrode containing at least one metal oxide and being transparent and a voltage being applied between said first and second electrode to detect a photocurrent;
• and
• an amorphous silicon multi-layer structure sandwiched between said pair of first and second electrodes, said multilayer structure comprising at least one first amorphous silicon layer which is in contact with said first electrode, which is doped with at least one of the metal elements which constitutes the electrode material of said first electrode and with oxygen atoms, and which has an optical bandgap in a range of 2.0 eV or above, a resistivity in a range of 10.sup.12 -10.sup.14 ohms-cm, a photoresistivity in a range of 10.sup.7 -10.sup.8 ohms-cm at AM 1100 mW/cm.sup.2 and a refractive index within the range of 1.8-3.4, and at least one second amorphous silicon layer, in surface contact with said second electrode, which is undoped.