Metal-semiconductor-metal (MSM) polysilicon photodetectors which are compatible with all standard complementary
metal-oxide-semiconductor (CMOS) processes and which were made in a commercial 0.35 ìm process have
demonstrated DC responsivities up to 1.3 A/W at 690 nm. An effective absorption coefficient of 0.63 dB/ìm was found
from a comparison of responsivities of 5- and 10-μm long detectors. For a constant bias voltage, responsivity varies as
the inverse square of the contact spacing, with responsivity continuing to increase for the smallest available contact
spacing devices. Responsivities corresponding to quantum efficiencies over 200% were observed, implying a gain
mechanism. For AC performance, electrical pulse full-width at half-maximum (FWHM) as low as 0.81 ns and 10% -
90% rise times as low as 0.39 ns have been measured in response to ~0.65 ns FWHM optical input pulses. The ability
to modulate the source laser diode limits the measured pulse performance of the detectors. Observed DC and pulse
results are well explained by an analytic expression which incorporates the effects of bulk and contact recombination.
Possible means of improving the detector speed are proposed.2
A novel, truly CMOS compatible, waveguide coupled, high-speed photodiode for on-chip optical clock distribution is designed using analytical calculations, electro-optical simulations, and experimental analysis. Experiment and simulation results from test devices are presented and analyzed.
A novel waveguide sensor capable of sensing multiple analytes directly and in real time with label-free, local detection has been investigated. Numerical simulations agree with analytical calculations of the sensor sensitivity. The waveguide parameters including detector to core distance, adlayer length, and surface roughness have been extensively analyzed. Initial experimental realization efforts are summarized.