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HL: Fachverband Halbleiterphysik

HL 58: Nitrides: Preparation and characterization I

HL 58.3: Vortrag

Donnerstag, 19. März 2020, 10:00–10:15, POT 112

Growth of AlN on Si(111) by reactive pulsed sputtering — •Florian Hörich, Jürgen Bläsing, Armin Dadgar, and André Strittmatter — Otto-von-Guericke University Magdeburg

Efficient, nitride-based UV light emitting diodes demand for AlN buffer structures with well-aligned crystallographic planes both in growth as well as in in-plane direction to enable low-defect densities within the subsequent layer stack. Currently, best crystallographic qualities are reported for sputtered AlN layers on sapphire substrates which are thermally annealed at temperatures up to 1700°C . This technique cannot be used with silicon substrates because of the lower melting temperature of Si. Thus, sputtering of AlN layers must be optimized to obtain low-defect density buffer structures on Si. We present our work on the growth of AlN on Si(111) by reactive pulsed sputtering, where growth temperatures below 800°C are used. The low growth temperature aims at reducing thermal stress in the epitaxial layer. We examine the effect of an Al seed layer and the impact of the nitrogen source for the crystalline quality. The thickness of the Al seed layer is critical and an optimum for a deposition time of 4 s (would correspond to a 0.2 nm Al layer) is found. Ammonia as nitrogen source is not favourable during growth of AlN directly onto the Si substrate. Since NH3 reacts with the Si surface forming SiN the growth of AlN is limited. With N2 as nitrogen source these limiting chemical reactions are not observed enabling AlN growth on top of the Al seed layer. For an AlN layer thickness of 40 nm the FWHM values of the XRD rocking curves are 0.65° (0002) and 1.35° (10-10).