Low Dark Count Rate and High Single Photon Detection Efficiency Avalanche Photodiode in Geiger-mode Operation

摘要

Recently, single photon avalanche detectors (SPADs) have been the subject of numerous research programs due to the emergence of applications such as, quantum cryptography, time resolved spectroscopy, three-dimensional imaging, and optical time domain reflectometry (OTDR). Silicon (Si) avalanche photodiodes (APDs) operated in Geiger-mode achieve very high detection efficiency and low dark count rate. However the bandgap of Si limits their operating wavelength to λ < 1.1μm. For longer wavelength operation, a great deal of research has been done on In{sub}0.53Ga{sub}0.47As/InP-based SACM (Separate-Absorption-Charge Multiplication) APDs as single-photon counters. Most of these studies have used commercially available APDs that were developed for fiber optic transmission. In this paper we report In{sub}0.53Ga{sub}0.47As/InP SPADs designed for low dark current that achieve record dark-count-rate/detection-efficiency performance. The SPAD structure is a 40μm-diameter planar In{sub}0.53Ga{sub}0.47As/InP-based SACM (Separate-Absorption-Charge Multiplication) APDs grown by MOCVD. The breakdown voltages at 297K and 200K were 62.3V and 51.6V, respectively (Fig. 1). The dark current at 95% of the breakdown voltage was 0.18nA and 0.15pA at 297K and 200K, respectively. Such low dark current is an indication of good crystal quality. Geiger-mode operation was characterized using pulse quenching. The SPAD was biased ～0.6V below the breakdown voltage and a 4ns voltage pulse was superimposed through a 30nF capacitor. The repetition rate was 10kHz. A pulsed laser source and a photon counter were synchronized with the voltage pulse. The pulsed laser diode produced optical pulses with width of 400ps at 1310nm. The optical source was attenuated to 0.1 photon per bias gate by a calibrated variable optical attenuator.