Low-noise AlGaAsSb avalanche photodiodes for 1550 nm 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.

High sensitivity InGaAs/AlGaAsSb avalanche photodiode with fast overload recovery and high damage threshold

“…Avalanche gain versus voltage was calculated by setting the gain at punch-through voltage (-30 V) to 1.5 as previously presented in ref. [10]. The unmultiplied responsivity value is 0.95 A/W [10].…”

“…AlGaAsSb-based SAM-APD is one of the most promising candidates for high-gain linear mode detection as it has demonstrated extremely high-temperature stability and low excess noise factor at high gain [8], [9]. Phlux Technology has reported an InGaAs/AlGaAsSb APD with a low dark current and excess noise factor which led to a 12 times improvement in sensitivity (noise equivalent power (NEP)) over a state-of-the-art APD when operated at high gain (M ~100) and integrated with a TIA [10]. In this study, we report on the progress in the temperature stability up to 85 ℃ (maximum operating temperature specified for military and civil applications) of our APDs and develop an APD-TIA receiver module for high gain linear mode few photons detection.…”

Development of InGaAs/AlGaAsSb Geiger Mode Avalanche Photodiodes

“…The InGaAs/AlGaAsSb APD wafer was grown on a semiinsulating InP substrate using molecular beam epitaxy. The wafers were designed and fabricated into mesa devices (using standard contact lithography and wet chemical etching) by Phlux Technology Ltd [30]. The InGaAs photon absorption layer and the AlGaAsSb avalanche layer are separated by a charge sheet to minimize the electric field and band-to-band tunneling in the InGaAs layer.…”

“…Recently, Al0.85Ga0.15As0.56Sb0.44 (AlGaAsSb) has emerged as a superior avalanche material for Linear mode APDs, with experimental reports of highly dissimilar ionization coefficients [28] and low excess noise factor [29] (resulting in very low Noise-Equivalent-Power [30]). Reported values of Cbd for a GaAsSb/AlGaAsSb SAM APD are ~4 mV/K [31], lower than equivalent InGaAs-based APDs with InP (~100 mV.K -1 ) [32] and InAlAs (~20-50 mV.K -1 ) [23][24][25][26] avalanche layers.…”

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.…”