NOVELTY - Vertical colour filter detector group formed on a semiconductor substrate comprises three detector layers configured to collect photo-generated carriers of a polarity, separated by additional intervening reference layers configured to collect and conduct away photo-generated carriers of the opposite polarity. The three detector layers are placed in vertical alignment with each other and have different spectral sensitivities as a function of their different depths in the semiconductor substrate.    USE - For active pixel sensors.    ADVANTAGE - Only NMOS transistors are used in the sensing circuitry, which compared to a structure that would use opposite polarity transistors for the green channel, has one half the control wires for a given pixel configuration, and occupies much less space because n-wells are not needed for PMOS devices as in conventional schemes. The simplest pixel support needed for the vertical colour filter detector group of the present invention requires only a total of six array wires running across the sensors. Additional colours may be sensed according to the present invention by adding additional layers and/or changing the junction depths. In addition, there is no image lag associated with the barrier gate mode that is sometimes used with pixel sensors. There is no interaction between the red, green, and blue photodiodes because of the isolation between sensors provided by the alternating-polarity diodes present in the structure. None of the problems associated with complementary array support circuits, such as phase lag associated with digital and analog level shifters, are present in the pixel sensor of the present invention. Finally, the junction depths of the pixel sensor of the present invention may be more closely matched to the optimal junction depths for absorption of the red, green, and blue wavelengths.    DETAILED DESCRIPTION - INDEPENDENT CLAIM is also included for the following:method of fabricating a vertical colour filter detector group    DESCRIPTION OF DRAWING(S) - The diagram shows a vertical colour filter pixel sensor employing epitaxial semiconductor technology    photodiodes (64,70,74)