An extrinsic silicon charge coupled device for detecting infrared radiation

The operation of an integrated infrared detector/charge coupled device structure is discussed. Silicon MOS/CCD processing technology has been used to fabricate CCDs with 8, 16, and 32 detector elements on silicon substrates doped with gallium (N_Ga - 6 × 10¹⁶/cm³). Performance of the device has been evaluated at infrared background generated currents ranging from 0. 15 to 50 picoamperes. Signal-to-noise ratios approaching 10⁴ have been measured, which indicates that a dynamic range of at least 80 db can be achieved. Background subtraction and overload protection circuits have been incorporated into the CCD. Signal bandwidth measurements have been made at several backgrounds and clock frequencies from 10 kHz to 100 kHz. The upper temperature limit for detector operation was about 20^oK. No anomalous charge transfer effects have been seen at operating temperatures as low as 8^oK.