Evolution of pyramid morphology during InAs(001) homoepitaxy

Abstract

Growth of InAs͑001͒ homoepitaxial layer has been carried out especially at the bistable region, where the coexistence of both In-stabilized ͑4 ϫ 2͒ and As-stabilized ͑2 ϫ 4͒ surface reconstruction are found to be predominant. The observation of pyramid morphology in this bistable region is reported here. Atomic force microscopy studies have been performed on such pyramids. The heights of the observed pyramids vary from 12 to 26 nm with their bases from 3.6ϫ 1.2 to 18 ϫ 6.3 m 2 . Formation of such pyramids in the bistable region is attributed to the unique anomalous As-desorption observed during the surface reconstruction. © 2010 American Institute of Physics. ͓doi:10.1063/1.3481077͔Atomic scale changes happening during the growth of III-V epitaxial layers by molecular beam epitaxy had played an important role in understanding the growth mechanism providing various information on nucleation, evolution of growth modes, defect formation, island formation, and surface reconstruction. There have been many reports explaining various surface informations during the homoepitaxial growth of III-V materials. Anisotropic mounds and island formation during the homoepitaxial growth of GaAs͑001͒, [1][2][3][4] periodic elongation of terraces in InP homoepitaxy, 5 straight edge formation on InAs͑001͒ vicinal surface 6 are few reports especially in homoepitaxy. The formation of such mounds, terrace, and islands, in general, the morphology of epitaxial films as the result of three-dimensional ͑3D͒ nucleation are mainly triggered by many parameters like V/III flux, substrate temperature, deposition rate, surface reconstruction, and the thickness of the growing epilayer.Among the various III-V compound semiconductors, InAs is attracted for long-wavelength, high carrier mobility, 7 high speed, and high frequency applications.8 Epitaxial thin films for post complementary metal-oxide-semiconductor digital integrated circuits 9 and high performance spin devices 10-12 require the surfaces to be atomically smooth with low defect densities in critical conditions. However the formation of 3D structures or islands on the III-V surfaces is found to be an important study to explore the growth mechanism. The effects of such surface modifications have shown some confinement on characterizing such surfaces. 13 On the other hand, investigation on the surface morphology remains important on realization of high quality heterostructures. There have been few theoretical investigations on InAs͑001͒ surface to elucidate the growth mechanism.14-18 Relatively few experimental work on the InAs͑001͒ surface were done which mainly concentrate on the surface reconstruction. 19-23Bell et al. 24 have investigated the islands and defects formation on InAs͑001͒ surfaces, whereas the growth was carried out at low temperatures. In this letter, we report mainly the analysis of InAs surfaces as a function of substrate temperature especially at high temperatures around ͑2 ϫ 4͒ to ͑4 ϫ 2͒ surface reconstruction. Previous reports on the growth of InAs layer at higher t...

Mid-infrared electroluminescence from InAs type-I quantum wells grown on InAsP/InP metamorphic buffers

“…2(d)], which is consistent with earlier observations that the InAs (4 Â 2) growth regime leads to a high density of microscale pyramid defects and high RMS roughness. [15][16][17] The specific RHEED transition temperatures are expected to depend sensitively on the InAs x P 1Àx composition, V/III ratio, and method of temperature measurement. However, these results show the importance of staying within a (2 Â 4) regime in order to maintain smooth surface morphology.…”