Annealing-induced structural changes in TlInGaAsN heterostructures studied by X-ray photoelectron spectroscopy

Rapid thermal annealing (RTA) improves the photoluminescence (PL) efficiency of TlInGaAsN semiconductor alloys, but the blue-shift of PL peak wavelength occurs. TlInGaAsN thin films grown by gas-source molecular-beam epitaxy were investigated by X-ray photoelectron spectroscopy (XPS) to study the annealing-induced transformation of the atomic configurations. XPS analysis revealed that the dominant atomic configuration of the TlInGaAsN changes from In-As and Ga-N bonds to the In-N and Ga-As bonds by RTA at 700°C for 1min. High-resolution X-ray diffraction and reciprocal space mapping measurements showed that no significant out-diffusion of the elements occurs in TlInGaAsN/TlGaAsN quantum wells (QWs) even after the same annealing condition. It is concluded that the blue-shift in the PL peak for the TlInGaAsN/TlGaAsN QWs after annealing is attributed to the changes of the atomic configuration in TlInGaAsN.