Berlin 2008 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 9: Semiconductor Nanophotonics: Materials, Models, Devices - GaN based Photonics II

DS 9.1: Hauptvortrag

Montag, 25. Februar 2008, 16:00–16:30, H 2032

GaN-Photonics on Silicon — •Alois Krost — Institute of Experimantal Physics, Otto-von-Guericke University Magdeburg

In spite of large efforts there is still a lack of available homosubstrates for group-III nitrides. Currently, GaN-based devices are usually grown on transparent sapphire or Silicon carbide substrates. These are either insulating or very expensive and not available in large diameter. Silicon is the substrate of choice because of its cheapness, availability of large and high-quality substrates combined with good thermal conductivity and insulating or conductive electrical properties. In the last years fundamental problems such as the huge thermal mismatch leading to cracks have been overcome by several approaches such as (Al,Ga)N buffer layers, low-temperature AlN interlayers, or growth on patterned substrates. Most of the recent work and published device results have been for GaN growth on (111) silicon substrates, with the first commercial chips, mainly HEMTs, now available by several companies with diameters up to 150 mm. Meanwhile, we have also obtained the first MOVPE-grown, crack-free, GaN-based LED on (100) silicon after the insertion of multiple AlN interlayers in the buffer structure paving the way towards integrated optoelectronics with GaN-on-Silicon technology. However, for optoelectronics the situation is more challenging than with electronic applications because Si is a non-transparent substrate and 94 % of the generated light is absorbed. Thus, GaN-on-Si LEDs cannot compete with those on transparent substrates unless substrate removal is performed. Our latest results on this topic will be reported.