Excitation intensity dependence of lateral photocurrent in InGaAs/GaAs dot-chain structures

• Lateral photoconductivity of InGaAs quantum dot-chains is studied.
• Carrier generation and recombination at deep defects and dot arrays are considered.
• Radiative recombination results in nonlinear photocurrent with excitation intensity.
• Quantum dot photocurrent nonlinearities are found to be thermally activated.

Optical properties of multi-layer InxGa1 − xAs/GaAs dot-chain heterostructures are studied by means of lateral photoconductivity (PC). Effects of carrier generation and recombination on the photoresponsivity of deep defects and quantum dot arrays are considered. It is shown that the radiative recombination significantly affects the lateral PC spectra thus leading to a nonlinear dependence of photocurrent on excitation intensity. For ground state excitation of the quantum dots the photocurrent nonlinearities are determined by a competition of both generation and recombination processes which include thermal activation.