Growth And Annealing Temperature Study Of Nonpolar GaN

Due to the conventional GaN grown on polarity c surface sapphire substrate.Itresulted with strong polarization effect which is useful for high electron mobilitytransistor.These polarization fields are undesirable for light emitting devices whoseactive regions consist of quantum wells, because the associated electric fields separatethe electrons and holes at the opposite interface of the well and reduce the overlap oftheir wave functions. This result in a reduction of the recombination efficiency in lightemitting devices.To eliminate the internal polarization fields, group III nitride layershave been recently grown on nonpolar planes, such as the a plane. However, extendeddefect densities in nonpolar a plane (11-20) GaN are very high. In this paper, we studythe nonpolar GaN materials. The main innovative results are:1. Using the home made MOCVD system, the high quality nonpolar a plane GaNcrystal film with on r plane sapphire has been achieved. Through the study oftemperature and pressure which influence on nonpolar a plane GaN growth quality, Wefound that the growth temperature at1020and growth pressure at80torr the surfacequality is relatively good, extended defect densities are low.2. In order to reduce the concentration of O, make good effect of p type doping,this paper puts forward a kind of Ⅴ/Ⅲ ratio gradient type nonpolar GaN growthstructure, Ⅴ/Ⅲ ratio is1000,1580,2550respectively. This structure growth of nonpolara plane GaN material quality is similar to low Ⅴ/Ⅲ ratio of nonpolar a plane GaNmaterial quality.3. We studied that Mg doped nonpolar a plane GaN material annealing temperature.The study found that in750annealing, surface morphology is the best, impuritydoping concentration is the highest, carrier mobility is the biggest. So we can concludedthat the best annealing temperature of nonpolar a plane GaN material is about750.