Study On Dislocation And Stress Of In_0.82Ga_0.18As Epitaxial Layer With Different Buffer Layers

In_xGa_1-xAs,a ternary semiconductor material,is widely used in the field of infrared detectors because it can well cover infrared radiation in the range of 1-3?m.In addition,In_xGa_1-xAs is also one of the most important basic materials for many optoelectronics devices as a result of its excellent optical and electrical properties,such as high electron mobility and optical absorption coefficient.With the improvement of technology,the preparation methods of In_xGa_1-xAs materials have also been developed maturely and diversifiedly.However,the lattice mismatch between the epitaxial layer and the substrate as well as the resulting large number of defects have always been unavoidable problems in the epitaxial growth of In_xGa_1-xAs materials with high in content.Up to now,no substrates can well match with the epitaxial layer,which limits the quality of In_xGa_1-x-x As materials and the performance of relevant devices.In order to overcome this problem,scientists have made a variety of attempts,among which the more commonly used and mature method is to introduce buffer layer into the epitaxial system.But the influence factors of buffer layer are various.Therefore,it is of great significance for the subsequent application of In_xGa_1-xAs materials in the future to carry out the work of In_xGa_1-xAs epitaxial growth on substrates and introducing buffer layer,clarify the distribution and variation of dislocations in the epitaxial layer,and explore the influence of structure of buffer layer on the quality and properties of the epitaxial material.In this paper,In_0.82Ga_0.18As epilayers were grown on InP substrates by low pressure metal organic chemical vapor deposition?LP-MOCVD?method,and different buffer layers were inserted between the substrates and the epitaxial layers.By means of scanning electron microscopy?SEM?,Raman scattering spectroscopy,double crystal X-ray diffraction?DC-XRD?and transmission electron microscope?TEM?,the effects of different single buffer layer,graded buffer layers and superlattice buffer layers on the quality and performance of In_0.82Ga_0.18As epitaxial layer were investigated.The main research contents are as follows:?1?With the increase of In content of the inserted In_xGa_1-xAs buffer layer,the crystallization quality of the epitaxial layer is increased,the dislocation density is reduced,and the electrical properties are also improved.Especially,the quality of In_0.82Ga_0.18As epitaial layer is relatively optimal when inserting In_0.82Ga_0.18As buffer layer,which is positively mismatched with InP substrate and perfectly matched with In_0.82Ga_0.18As epitaxial layer.?2?For In_0.82Ga_0.18As/InP heterostructures with graded or superlattice buffer layers,the In_0.82Ga_0.18As epilayers are affected to different degrees.Compared with the heterostructure with single In_0.82Ga_0.18As buffer layer,the stress release in the epitaxial layer with In_xGa_1-xAs graded buffer layer is faster,and the multiple buffer space and interfaces can effectively accommodate and block the dislocations,so the improvement of the quality is more obvious.When introducing In_0.82Ga_0.18As/In_0.82Al_0.18As superlattice buffer layers into the In_0.82Ga_0.18As/InP heterostructure,the dislocation density of In_0.82Ga_0.18As epitaxial layer reaches the lowest value under the combined action of the potential well layer and barrier layer distributed alternately,and its crystalline quality and electrical property are relatively best.?3?The residual stresses in In_0.82Ga_0.18As epitaxial layer with different types of buffer layers were qualitatively and quantitatively analyzed by Raman scattering spectroscopy and nanoindentation technique.