Research On The Process Of GaN Grown By HVPE

With the development of information technology, semiconductor technology and the corresponding study of semiconductor materials are becoming more and more important. Gallium nitride as a wide band-gap compound semiconductor offers attractive properties such as high thermal conductivity and high electron saturation velocity for microelectronic devices.In this article, GaN layers were grown by hydride vapor-phase epitaxy (HVPE) on sapphire substrates and on GaAs substrates. The quality of the grown layers on these two types of substrates is studied by using X-ray double diffraction (XRD),scanning electron microscopy (SEM),atomic force microscope (AFM),PL spectrum and differential interference microscopy (DIC). In addition, the laser lift-off of GaN and sapphire substrate is also a major work of this article.The Al₂O₃ substrate was employed to growth GaN, The surface morphology of the GaN layers grown on sapphire substrate with different off-orientations was measured. The results shown optimum off-orientation was approximately 0.2°could make the epitaxial layer surface more smooth. Additionally, appropriate amount of carrier gas andⅤ/Ⅲratio can improve the quality of GaN. The experiment results show that when the N₂ flow are 4000ml/min andⅤ/Ⅲrate is 30, a high quality GaN layer with smaller FWHM of PL spectra and good luminescence capability can be got.The GaAs substrate was employed to growth GaN, the substrate would decompose at high growth temperature. For solving this problem, the nitride layer was firstly formed on GaAs substrate surface using NH₃ at low temperature, a uniformity buffer layer was then growth. On this basis, higher quality thick film single GaN crystal can be produced.For separating the GaN single from the sample of GaN/Sapphire template, UV laser (LLO) was used. In this research, the parameters of the laser power, the facular size, the temperature of system, and the scan path of the laser were adjusted and optimized. As a result, the damage thickness of the GaN wafer was reduced and gallium nitride thick films grown on sapphire substrates were successfully separated.