Light-Emitting AlGaAs/GaAs Diodes Based on InGaAs Strain-Compensated Quantum Wells with Minimized Internal Losses Caused by 940-nm Radiation Absorption

Abstract

IR light-emitting diodes (LEDs) based on InGaAs/AlGaAs multiple quantum wells (MQWs) and Al_xGa\(_{{1-x}}\)As_yP\(_{{1-y}}\) layers, compensating stress in the active area, have been developed. The optical losses caused by absorption of the radiation generated by the active area (λ = 940 nm) have been investigated at different doping levels of n-GaAs substrates. It is shown that reduction of the donor doping level from 4 × 10¹⁸ to 5 × 10¹⁷ cm^–3 gives an increase in the LED quantum efficiency of ~30%. A technology making it possible type to eliminate completely the optical losses caused by absorption during radiation output has been developed. Removal of the substrate and transfer of the device structure to a carrier substrate with formation of a rear metal reflector made it possible to create LEDs demonstrating a twofold increase in the external quantum efficiency (EQE) and efficiency (~40%) as compared to the technology of radiation output through an n-GaAs substrate.