Low-noise AlGaAsSb avalanche photodiodes for 1550nm light detection

Abstract

The optical detector used in pulsed LIDAR, range finding and optical time domain reflectometry systems is typically the limiting factor in the system's sensitivity. It is well-known that an avalanche photodiode (APD) can be used to improve the signal to noise ratio over a PIN detector, however, APDs operating at the eye-safe wavelengths around 1550 nm are limited in sensitivity by high excess noise. The underlying issue is that the impact ionization coefficient of InAlAs and InP used as the avalanche region in current commercial APDs are very similar at high gain, leading to poor excess noise performance. Recently, we have demonstrated extremely low noise from an Al(Ga)AsSb PIN diode with highly dissimilar impact ionization coefficients due to electron dominated impact ionization.In this paper, we report on the first low noise InGaAs/AlGaAsSb separate absorption, grading and multiplication APDs operating at 1550 nm with extremely low excess noise factor of 1.93 at a gain of 10 and 2.94 at a gain of 20. Furthermore, the APD's dark current density was measured to be 74.6 µA/cm 2 at a gain of 10 which is competitive with commercial devices. We discuss the impact of the excess noise, dark current and responsivity on the APDs sensitivity and, project a noise-equivalent power (NEP) below 80 fW/Hz 0.5 from a 230 µm diameter APD and commercial transimpedance amplifier (TIA). The prospects for the next generation of extremely low noise APDs for 1550 nm light detection are discussed.

Anomalous excess noise behavior in thick Al0.85Ga0.15As0.56Sb0.44 avalanche photodiodes

“…The small difference in F between PIN1 and PIN2 is probably due to the differences in avalanche widths and background doping between the structures. Although these F are obtained using 455 nm light, on structures representing just the multiplication regions, near identical results have been obtained in Al 0.85 Ga 0.15 AsSb using wavelengths of 1450-1550 nm when combined with a low electric field InGaAs 18 or GaAsSb 19 absorber as shown in Fig. 3b.…”

Low-noise AlGaAsSb avalanche photodiodes for 1550 nm light detection

“…A gain of 10 is reached at a reverse voltage of 55.5 V. At this voltage, the dark current of this APD is 7.0 nA which corresponds to a dark current density of 16 μA/cm 2 . This is lower than our previous report 5 and commercial 1550 nm wavelength APDs available from Hamamatsu (20 nA) 8 , Excelitas (45 nA) 9 and Laser Components (25 nA) 10 .…”

“…Phlux Technology have previously reported an InGaAs/AlGaAsSb SAM APD, with excellent low excess noise properties of F = 1.93 and 2.94 at gains of 10 and 20 respectively 5 . In this study, we report further improvements made to the design, fabrication and reliability which have improved the APD's excess noise, gain and dark current characteristics.…”

Very high gain and low noise GaAsSb/AlGaAsSb avalanche photodiodes for 1550nm detection at room temperature

“…Al0.85Ga0.15AsSb (hereafter AlGaAsSb) has demonstrated reduced surface dark currents and very low excess noise characteristics 11,12 . By combining AlGaAsSb with either an InGaAs 13,14 or GaAsSb 15,16 absorber, it has achieved very high sensitivity at 1550 nm along with high bandwidth 17 . Lee et al 16 demonstrated that GaAsSb/AlGaAsSb can achieve a high gain of 278 at room temperature with excess noise F<3 at M=60.…”