Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 69: Nitrides: LEDs

HL 69.4: Vortrag

Donnerstag, 17. März 2011, 11:00–11:15, POT 51

High n-type crack-free GaN layers on Si substrates by Ge doping — •Armin Dadgar, Jürgen Bläsing, Annette Diez, and Alois Krost — Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg

GaN based growth on silicon substrates usually requires strain-engineering methods to avoid tensile stress after cooling from growth temperature. Silicon doping required for contacting and current spreading is known to induce additional tensile stress during growth originating in edge dislocation climb. Consequently, the typically inferior material quality for GaN on Si in comparison to GaN grown on sapphire leads to high tensile stresses for highly Si doped layers, limiting freedom in device design and performance. We present that germanium doping enables the growth of thick highly n-type doped layers on silicon substrates not influencing strain evolution. By this, it enables a possible improvement of GaN-on-Si LEDs. We also conclude that the mechanism of dislocation climb in the case of silicon doping is not dominated by surface roughening but by silicon-nitride induced dislocation masking which does not apply for germanium.