Low-temperature operation of silicon surface-channel charge-coupled devices

This paper presents results of the measurement and modeling of the temperature dependence of the charge-transfer inefficiency (CTI) on n- and p-channel surface-channel charge-coupled devices (CCD's) over the 25-300 K temperature range. The CTI was measured at clocking frequencies of 1, 10, and 40 kHz with minimum values of 0.00075 and 0.00018 reached near 50 K for the n- and p-channel devices, respectively. The CTI was modeled in terms of the interaction of the signal charge with an energy-dependent interface state density distribution. At temperatures above 200 K, thermally generated carriers or dark current modify the simple dependence on the interface state density distribution. The two-part model correctly simulates the dependence of the CTI on both the temperature and the frequency of operation. Fractional loss measurements were used to study surface state parameters. Other features of CCD low temperature operation measured and modeled include the input stage equilibration process.