Investigation of strain in an oxide-confined GaAs/AlGaAs PIN heterostructure through spot-dependent photoluminescence spectroscopy
We report on the observation of strain in an oxide-confined gallium arsenide/aluminum gallium arsenide (GaAs/AlGaAs) PIN heterostructure through spot-dependent photoluminescence (PL). The PIN structure was grown via molecular beam epitaxy. The layers were etched into 250 μm cylindrical mesa structures and thermally oxidized. Room temperature photoluminescence (PL) measurements were done using a micro-PL setup equipped with a motorized stage. The AlGaAs PL peak at the oxidized region of the PIN structure was observed to redshift by ~10.3 meV from the PL measured at the unoxidized region located at the center of the mesa. This redshift is attributed to the tensile strain on the AlGaAs layers on top of the aluminum arsenide (AlAs) layer that has been converted to aluminum oxide (Al2O3). This technique provides a quick way of measuring the strain in heterojunction-based devices such as vertical-cavity surface emitting lasers.