Antimonide based Separate Absorption Charge and Multiplication Avalanche Photodiode

A room temperature, ultra-high gain (M=278, λ=1550 nm, V=69.5 V, T=296 K) linear mode avalanche photodiode (APD) on an InP substrate using a GaAs0.5Sb0.5/Al0.85Ga0.15As0.56Sb0.44 separate absorption charge and multiplication (SACM) heterostructure.

The Need

An APD is a semiconductor-based analog of the photomultiplier. APDs exploit the impact ionization phenomenon and transform infrared (IR) light (l > 850 nm) into photocurrent. APDs have wide applicability; however, existing APDs have insufficient sensitivity and relatively high excess noise and dark current.

The Technology

A new complex APD consisting of different layers grown on InP is suggested. It has a heterostructure of GaAsSb/AlGaAsSb, which consists of separate absorption charge and multiplication in the linear mode avalanche photodiode. This novel APD has a stoichiometric formula of GaAs0.51Sb0.44 (GaAsSb IR light absorber) instead of the conventional InGaAs APDs. This discovered structure has outstanding properties. This includes high gain and low excess noise.

Commercial Applications

The invented APD can be utilized in various measurements requiring high sensitivity, including telecommunications, photochemistry, particle physics, positron emission tomography, laser rangefinders, and remote sensors of greenhouse gases.


The new APD can be used as an IR light highly sensitive receiver at eye-safe wavelengths (l =1400 - 1650 nm) for various applications. The excess noise factor is extremely low (F<3) at M=70, and this design gives a quantum efficiency of 5935.3% at maximum gain.


Provisional patent applications filed.

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