Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 47: GaN on Si

HL 47.4: Talk

Wednesday, March 16, 2011, 11:00–11:15, POT 51

Monitoring the influence of interlayer thickness and Si doping on the stress behaviour of GaN grown on Si(111) — •S. Fritze¹, J. Bläsing¹, P. Drechsel², A. Dadgar¹, and A. Krost¹ — ¹Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Universitätsplatz 2, 39106 Magdeburg — ²OSRAM Opto Semiconductors, Leibnizstraße 4, 93055 Regensburg

GaN growth on Si substrates is a cost-effective alternative to replace conventional substrates like sapphire and SiC. Especially the large diameter availability of Si substrates up to 300 mm can increase chip yield and reduce production costs. To accomplish thick, crack free GaN layers of high crystalline quality an exact control of tensile thermal stress between GaN and Si and the reduction of high dislocation densities are essential. By inserting thin AlN interlayers during growth compressive stress is induced in the subsequent GaN layer and compensates part of the tensile stress. Here the influence of interlayer thickness and Si doping on wafer bow, crystal quality and vertical strain profile of MOVPE grown GaN structures on Si(111) has been studied. In symmetric and grazing incidence high resolution X-ray diffraction measurements we observe higher compressive stress in the GaN toplayer with increasing interlayer thickness. Additional X-ray transmission scattering measurements also show the stress state of the underlying GaN layers. Optical bow measurements demonstrate an increasing convex curvature with increasing interlayer thickness. With a Si doping level between 1·10¹⁸cm⁻³ and 4·10¹⁸cm⁻³ a wafer bow as low as 2.9 µm can be achieved using an optimized interlayer thickness.