The optical characterization of indium(y) gallium(1-y) arsenic(1-x) nitrogen(x)

Abstract

The dilute Nitride materials, InGaAsN, are studied as promising candidates for optical devices in the telecommunications wavelength range between 1.3 and 1.55mum. Such materials can be grown lattice matched to a GaAs substrate and could remove the need to work with structures based on the InGaAsP/InP materials, which are expensive and have poor temperature performance. There are three main growth techniques for InGaAsN materials, chemical beam epitaxy (CBE), molecular beam epitaxy (MBE), and metal organic chemical vapour deposition (MOCVD). Of these three, MBE and MOCVD are used to grow the structures discussed in this thesis. X-ray diffraction and photoluminescence measurements are used for characterization. X-ray diffraction measurements provide the nitrogen concentration in the material, while photoluminescence measurements give the bandgap energy. The combination of these two results are then compared to the results from a band anti-crossing model that predicts the bandgap energy as a function of Nitrogen concentration. In addition, absorption and photoluminescence excitation measurements are used to investigate the Stokes shift in GaAsN material likely to have large composition non-uniformities. To illustrate the progress made with InGaAsN material growth, processing and characterisation, a broad area laser structure is demonstrated that emits around 1.3mum.