LAUSR

In this study, InGaN/GaN/Al 2 O 3 multi-quantum well (MQW) structure is investigated in 300–450 °C growth temperature range with steps of 50 °C. By the help of lattice constants at four different growth temperatures strain values are gained. Plot of strain in a- versus strain in c- is used to determine Poisson’s ratio for GaN in the structure. Poisson’s ratio is determined as 0.36. Reciprocal space mapping (RSM) technique of X-ray diffraction (XRD) method is used to gain peak positions of the sample instead of w – θ scans because it gives more accurate results. Shifts in peak positions by variations of growth temperatures are shown. Lattice parameter equations are used with τ modification angles which minimise the errors caused from tilt of c- in hexagonal unit cell. This work is original because Poisson’s ratio of GaN is determined using a natural method, variations in growth temperatures. It is also emphasised that RSM is a more sensitive method of XRD for determining structural properties of nitrite-based semiconductors.