Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 51: GaN: Pr
äparation und Charakterisierung III

HL 51.10: Vortrag

Dienstag, 8. März 2005, 13:00–13:15, TU P-N202

Heteroepitaxial Growth of Group III-Nitrides on Diamond — •Olaf Weidemann, Martin Hermann, Markus Maier, Martin Stutzmann und Martin Eickhoff — Walter Schottky Institut, Technical University Munich, Am Coulombwall 3, D-85748 Garching, Germany

The combination of group III-nitrides with diamond allows to overcome several basic problems of the individual material systems such as the lack of band-gap engineering in diamond, the substrate thermal conductivity of group III-nitrides or the doping problem. It is challenging to produce n-type diamond and, up to date, p-type doping of AlN has not been realized. However, the combination of p-type diamond with n-type AlGaN allows the fabrication of UV light emitting diodes. in addition diamond as a substrate is an excellent heat sink for high power devices.

We have studied the influence of diamond surface termination (O or H) and orientation {(001) or (111)} on the growth of group III-nitrides. We have deposited epitaxial layers (GaN, AlN), which were subsequently overgrown with a GaN/AlGaN/GaN heterostructure. High resolution X-ray diffraction measurements were performed to determine the crystal quality and orientation with respect to the diamond substrate. Due to the pyro- and piezoelectric character of group III-nitrides, close to one of the interfaces a two-dimensional electron gas (2DEG) is formed. Using capacitance-voltage profiling, the position of the 2DEG and thus the polarity of the material can be determined.