Abstract
Single photon avalanche diodes (SPADs) are key enabling technologies for a wide range of applications in the near-infrared wavelength range. Recently, AlAs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.56</sub> Sb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.44</sub> (hereafter AlAsSb) lattice-matched to InP has been demonstrated for extremely low excess noise avalanche photodiodes (APDs) due to its large disparity between electron and hole ionization coefficients ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> respectively). The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha /\beta $ </tex-math></inline-formula> ratio also plays a role in Geiger mode operation as it affects the avalanche breakdown probability and hence detection efficiency. In this work, we theoretically investigate the performance of AlAsSb based SPADs. The probability of breakdown for electron-initiated Geiger mode operation increases more sharply with multiplication region width due to progressively more dissimilar ionization coefficients. In comparison with other common avalanche materials, such as InAlAs, InP and Si, our result also suggests that SPADs based on AlAsSb have a sharper breakdown probability than the other three materials under similar low overbias ratio. The calculated breakdown probability of 0.81 in AlAsSb is 0.18 and 0.28 higher than that of InAlAs/Si and InP respectively at 5% overbias ratio and with avalanche region width of 1500 nm.
Highlights
S INGLE Photon avalanche diodes (SPADs) operating at near-infrared (NIR) wavelengths are of significant interest in several applications including quantum cryptography [1], CMOS circuit characterization [2] and eye-safe Light detection and ranging (Lidar) [3]
Itzer et al [6] reported that their InP SPAD has almost 10 times increase in dark count rate (DCR) when the overbias ratio increases from 7.5% to 15% to achieve desired single photon detection efficiency (SPDE)
We presented a model for AlAsSb avalanche photodiodes (APDs)/SPADs
Summary
S INGLE Photon avalanche diodes (SPADs) operating at near-infrared (NIR) wavelengths are of significant interest in several applications including quantum cryptography [1], CMOS circuit characterization [2] and eye-safe Light detection and ranging (Lidar) [3]. Itzer et al [6] reported that their InP SPAD has almost 10 times increase in DCR (from 8 kHz to 75 kHz) when the overbias ratio increases from 7.5% to 15% to achieve desired SPDE (from 18% to 37%) This significant increase in DCR is attributed to the field-assisted tunneling current [6]. Silicon (Si) based SPADs with germanium (Ge) absorber have been demonstrated for NIR wavelength range [8] Both InP and InAlAs have broadly similar α and β and are not optimal for achieving high detection efficiency, whereas Si which exhibits a larger α/β ratio has a large lattice-mismatch with Ge making device fabrication challenging. We investigate theoretically the performance advantages of AlAsSb based SPADs when compared to InP, InAlAs or Si
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