An epitaxially-grown charge modulation device

A charge modulation device (CMD) has been fabricated in a p-type epitaxial layer grown from the buried-channel silicon region of a charge-coupled device (CCD). Construction of the CMD directly above the CCD buried-channel and over the oxidized CCD transfer gates lowers the effective sense capacitance while providing isolation of the CMD source/drain regions. Responsivity values of 28 and 66 /spl mu/V/e for feedback and no feedback conditions, respectively, were measured dynamically on test devices. Input-referred noise values of approximately four electrons r.m.s. were calculated from noise spectral density measurements assuming a low-pass filter 3 dB cutoff frequency of 5 MHz and correlated double sampling.