InGaAs/InAlAs superlattice avalanche photodiode with a separated photoabsorption layer

Abstract

A novel structure superlattice avalanche photodiode is proposed. A p-InGaAs photoabsorption layer is separated from a nondoped InGaAs/InAlAs superlattice avalanche multiplication region. The electric field strength at the photoabsorption layer is controlled by a thin, highly doped p-InGaAs layer, which is sandwiched between the multiplication and photoabsorption layers. Devices with this structure were fabricated by molecular beam epitaxy. The external quantum efficiency is 73% at the multiplication factor of unity. The multiplication noise is quite small corresponding to an effective ionization rate ratio of 0.1. The maximum 3 dB bandwidth is 9.3 GHz.