GaAs and AlGaAs APDs with GaSb absorption regions in a separate absorption and multiplication structure using a hetero-lattice interface

Abstract

Interfacial misfit (IMF) arrays were used to create two APD structures, allowing GaSb absorption layers to be combined with wide-gap multiplication regions, grown using GaAs and Al0.8Ga0.2As, respectively. The GaAs APD represents a proof-of-principle, which is developed in the Al0.8Ga0.2As APD to achieve reduced dark currents, of 5.07μAcm−2 at 90% of the breakdown voltage, and values for effective k=β/α below 0.2. A random-path-length (RPL) simulation was used to model the excess noise in both structures, taking into account the effects of dead space. It is envisaged that the GaSb absorption regions could be replaced with other materials from the 6.1Å family, allowing for long-wavelength APDs with reduced dark currents and excess noise.