One of the key parameters determining detection properties of silicon PIN detector structures (p⁺-ν-n⁺ or n⁺-ν-p⁺) is minority carrier diffusion length in p-n junction regions p-n (p⁺-ν or n⁺-ν). The parameter concerned strongly depends on quality of the starting material and technological processes conducted and has a significant impact on detector parameters, in particular dark current intensity. Thus, the parameter must be determined in order to optimise the design and technology of detectors.

The paper presents a method for measuring the spatial distribution of effective carrier diffusion length in silicon detector structures, based on the measurement of photoelectric current of a non-polarised structure illuminated (spot diameter of 250 μm) with monochromatic radiation of two wavelengths λ₁ = 500 nm (silicon penetration depth of around 0.9 μm) and λ₂ = 900 nm (silicon penetration depth of around 33 μm). The value of diffusion length was determined by analysing the spatial distribution of optical carrier generation and values of photoelectric currents.

This study is based on the investigation of AlSb layer thickness effect on heavy−hole light−hole (HH−LH) splitting and band gap energies in a recently developed N−structure based on InAs/AlSb/GaSb type II superlattice (T2SL) p−i−n photodetector.eFirst principle calculations were carried out tailoring the band gap and HH−LH splitting energies for two possible interface transition alloys of InSb and AlAs between InAs and AlSb interfaces in the superlattice. Results show that AlSb and InAs−GaSb layer thicknesses enable to control HH−LH splitting energies to desired values for Auger recombination process where AlSb/GaSb total layer thickness is equal to InAs layers for the structures with InSb and AlAs interfaces