  Silicon single-photon detectors (SPDs) are key devices for detecting single
photons in the visible wavelength range. Photon detection efficiency (PDE) is
one of the most important parameters of silicon SPDs, and increasing PDE is
highly required for many applications. Here, we present a practical approach to
increase PDE of silicon SPD with a monolithic integrated circuit of active
quenching and active reset (AQAR). The AQAR integrated circuit is specifically
designed for thick silicon single-photon avalanche diode (SPAD) with high
breakdown voltage (250-450 V), and then fabricated via the process of
high-voltage 0.35-$\mu$m bipolarCMOS-DMOS. The AQAR integrated circuit
implements the maximum transition voltage of ~ 68 V with 30 ns quenching time
and 10 ns reset time, which can easily boost PDE to the upper limit by
regulating the excess bias up to a high enough level. By using the AQAR
integrated circuit, we design and characterize two SPDs with the SPADs
disassembled from commercial products of single-photon counting modules
(SPCMs). Compared with the original SPCMs, the PDE values are increased from
68.3% to 73.7% and 69.5% to 75.1% at 785 nm, respectively, with moderate
increases of dark count rate and afterpulse probability. Our approach can
effectively improve the performance of the practical applications requiring
silicon SPDs.
