Absorption of guided modes in light emitting diodes

摘要

The absorption of lateral guided modes in light emitting diodes is determined by the photocurrent measurement method. A theory for waveguide dispersion is presented and extended by ray-tracing simulations. Absorption coefficients of InGaN-on-sapphire and AlGalnP-based structures is evaluated by comparison with simulation curves. For nitride-based samples with emission wavelengths of 415 nm and 441 nm an absorption of 7 cm~(-1) is obtained. It is found that scattering is present in the buffer layer and influences the lateral intensity distribution. The investigated AlGalnP-based sample exhibits an absorption of α = 30 cm~(-1) at 650 nm emission wavelength.